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Why do we find flowers attractive?


Given that we (humans) are not evolutionarily closely related to bees, why do we find flowers attractive?


Sure, flowers can be sign that the fruit is underway as @JonathanMoore said and viewing any trait as a result of selection is probably what the OP was waiting for. Thinking that if an organism produces a behaviour, then this behaviour must have been selected is wrong though.

The reality is that specific behaviours are affected by evolution of other behaviours and other traits as well as an by our environment (incl. social environment). It will be particularly difficult to hypothesize as for the different selection pressures that may have existed on a specific behaviour especially in animals with such high cognition as humans. Maybe we like flowers because we like colour contrast and maybe we like colour contrast because face with stronger colour contrast is more attractive because it is a sign of health. Maybe we like sunset because we like flowers. Maybe we like colour contrast because we like fresh fruits. Maybe, we like complex design because it makes us think about the possible complexity of shapes. Maybe we like complex shapes because we like to explore. Maybe we like simple design because we like clear skins. Maybe we like flowers because of the diversity of shapes. Maybe we like flowers because they are a sign of the end of the cold winter. Maybe we like flowers because we are being told that they are pretty things. Maybe we like flowers because it symbolizes abundance and reproduction. Anyone could formulate loads of hypotheses. Maybe we like flowers because we like any smell that is not the smell of something that is rotting. Maybe we like flowers because we like trees, leaves, mountains, rivers, lakes and pretty much anything else in our natural surrounding. Maybe we like flowers because flowers is a sign that there is not no pests in our garden or simply that the plant we are growing is healthy.


Flowers are a sign that fruit is on its way, so it would be advantageous for us to remember the place where we saw flowers.


The abominable mystery: How flowers conquered the world

It was, Charles Darwin wrote in 1879, "an abominable mystery". Elsewhere he described it as "a most perplexing phenomenon". Twenty years after the publication of his seminal work The Origin of Species, there were still aspects of evolution that bothered the father of evolutionary biology. Chief among these was the flower problem.

Flowering plants from gardenias to grasses, water lilies to wheat belong to a large and diverse group called the angiosperms. Unlike almost all other types of plants, they produce fruits that contain seeds. What worried Darwin was that the very earliest samples in the fossil record all dated back to the middle of the Cretaceous period, around 100 million years ago, and they came in a bewilderingly wide variety of shapes and sizes. This suggested flowering plants had experienced an explosive burst of diversity very shortly after their origins &ndash which, if true, threatened to undermine Darwin's entire model of gradual evolution through natural selection.

In fact recently published research has revealed that angiosperms evolved relatively gradually after all. Yet this still leaves a number of key questions. The roughly 350,000 known species of flowering plants make up about 90% of all living plant species. Without them, we would have none of our major crops including those used to feed livestock, and one of the most important carbon sinks that mop up our carbon dioxide emissions would be missing. How and where did they originate? And, perhaps more importantly, why did they become so spectacularly successful?

Darwin was an undoubted expert on origins. His remarkable insights helped establish a framework for the way new species form &ndash and he was adamant that the process was slow and gradual.

"As natural selection acts solely by accumulating slight, successive, favourable variations, it can produce no great or sudden modification it can act only by very short and slow steps," he wrote in The Origin of Species.

But Darwin was painfully aware that there were apparent exceptions to his slow and steady rule. The angiosperms were a particular source of frustration. Angiosperms simply didn't exist for most of Earth's history. Early forests were populated by bizarre primitive tree-like plants closely related to the club mosses and horsetails that are a very minor part of today's plant communities. Later a group called the gymnosperms &ndash plants with unenclosed seeds such as the conifers &ndash took over. And then came the angiosperms.

Early in the 19th century, scientists like Adolphe-Théodore Brongniart began collating everything that was then known about fossil plants. Work like this highlighted the fact that a huge variety of angiosperms &ndash often called the "higher plants" or dicotyledons in the 19th century &ndash popped up all too suddenly in the middle of the Cretaceous geological period.

The sudden appearance of flowering plants was more than just perplexing. It was ammunition against Darwin's evolutionary model

"[The] sudden appearance of so many Dicotyledons&hellip appears to me a most perplexing phenomenon to all who believe in any form of evolution, especially to those who believe in extremely gradual evolution," Darwin wrote to Swiss naturalist Oswald Heer in 1875.

He was well aware the sudden appearance of flowering plants was more than just perplexing. It also provided his critics with ammunition against his evolutionary model.

Darwin did suggest a solution, however. Angiosperms, he said, may have evolved gradually in a remote region of the world as yet unexplored by scientists. By the middle of the Cretaceous, something caused them to spill out of their homeland and rapidly spread across the world. This, reasoned Darwin, would give the misleading impression to researchers working in Europe and North America that a wide variety of flowering plant species had all evolved at the same time. Aware of the lack of evidence to back up his theory, Darwin described it as "wretchedly poor".

In fact, his speculation has since proved to be partly correct. Angiosperms that predate the middle Cretaceous specimens by tens of millions of years have begun to turn up in rocks from China. But Darwin didn't get the details entirely right because very rare early angiosperms have been found in Europe and the US too.

"Our knowledge has greatly increased since the end of the 19th century," says Laurent Augusto at the National Institute for Agricultural Research in Bordeaux, France. Palaeobotanists may not yet agree on precisely where and when flowering plants first evolved, but their appearance in the fossil record much earlier than was previously known means they are no longer a problem for Darwin's theory of gradual evolution. Other debates about them, especially concerning their spectacular diversity, remain active, however.

"Our world is an angiosperm world," says Augusto. "In many ecosystems they dominate in species and in biomass &ndash this angiosperm ecological dominance remains unexplained."

Clues to the ultimate origins of flowering plants are to be found on New Caledonia, a small island about 1,600 kilometres east of Australia. Here, around the time that Darwin was agonising over his angiosperm problem, botanists discovered a plant called Amborella. Careful study over the last century has shown it to be the sole survivor of one of the very earliest branches of the angiosperm evolutionary tree. This means its relationship to all living flowers is bit like that of the duck-billed platypus to all living mammals: it might look unassuming, but Amborella can tell us more than even the most elaborate orchid about how the angiosperms first evolved.

Last year, the plant finally spilled some of its secrets. The Amborella Genome Project unveiled a draft version of the plant's genome. The first angiosperms must have evolved from one of the gymnosperm species that dominated the world at the time. The Amborella genome suggests that the first angiosperms probably appeared when the ancestral gymnosperm underwent a 'whole genome doubling' event about 200 million years ago.

Flowers have been a defining feature of the angiosperms from very early on in their evolution

Genome doubling occurs when an organism mistakenly gains an extra copy of every one of its genes during the cell division that occurs as part of sexual reproduction. The extra genetic material gives genome doubled organisms the potential to evolve new traits that can provide a competitive advantage. In the case of the earliest angiosperms, the additional genetic material gave the plants the potential to evolve new, never-before-seen structures &ndash like flowers. The world's flora would never be the same again.

The Amborella genome results strongly suggest that flowers have been a defining feature of the angiosperms from very early on in their evolution. Could the flowers themselves help explain why the angiosperms became so diverse?

Darwin was certainly open to the possibility. While he was wrestling with the problem posed by the seemingly sudden appearance of the angiosperms, he received a letter from Gaston de Saporta, a French biologist who said the apparent evidence of the 19th century fossil record suggesting the plant group appeared suddenly need not be a problem for Darwin's theory of gradual evolution. It simply showed that angiosperms were an unusual exception to his general rule. Flowering plants and their insect pollinators evolved together, reasoned Saporta, and this 'co-evolution' drove both groups to diversify unusually rapidly.

"Your idea &hellip seems to me a splendid one," responded an enthusiastic Darwin. "I am surprised that the idea never occurred to me, but this is always the case when one first hears a new and simple explanation of some mysterious phenomenon."

But the theory runs into trouble today, says Augusto. Early angiosperms may have had flowers, but we now know from fossils that those first flowers were very plain - and probably not that attractive to pollinators. By the time the big, bold flowers that entice insects appeared, the angiosperms were already diverse.

Another theory, advanced by Frank Berendse and Marten Scheffer at Wageningen University in the Netherlands in 2009, rests on the fact that the angiosperms are much more productive than gymnosperms like the conifers. Perhaps they simply outcompeted rival plants by growing faster and gobbling up the lion's share of the nutrients, they suggested.

"Our paper was meant to be a bit provocative," says Berendse, to encourage botanists and those who study fossil plants to work together more closely on explaining the spectacular rise of the angiosperms.

There are no simple explanations for the diversity and ecological dominance of the flowering plants

In fact, the two had already begun working together. Earlier in 2009, a team led by Tim Brodribb at the University of Tasmania in Hobart, Australia, published the first in a series of papers exploring angiosperm evolution by examining fossil leaves. They found that their leaves gained many more veins during the Cretaceous, which would have provided them with more water for photosynthesis, and allowed them to grow more rapidly.

"That provided very strong support for our ideas," says Berendse. But as with the flower hypothesis, problems remain with the nutrient-based theory. For instance, while individual angiosperm leaves are more efficient at photosynthesising than conifer needles, conifers may be able to compensate because their needles collectively have a much larger surface area than that of the leaves of an average angiosperm tree.

Unfortunately, there are no simple explanations for the diversity and ecological dominance of the flowering plants. "Very probably no single theory can explain the massive rise of the angiosperms," admits Berendse.

It's more likely, says Augusto, that several factors played a role, with each being more or less important in specific places and times. For instance, Berendse's productivity theory may apply in the tropical belts, where rich soils could give nutrient-hungry angiosperms a vital edge over gymnosperms, but it might not explain what's going on in regions with poor soils, where angiosperms are potentially starved of the nutrients they need. And the simple flowers of early angiosperms may have done little for the evolution of the group, but when elaborate flowers finally appeared they probably did help drive the plant group to take over the world.

That is, if they really did take over the world. It might seem odd to suggest otherwise when there are something like 350,000 known angiosperm species and not many more than 1000 gymnosperms, most of which are conifers. But there's more to success than diversity, says Brodribb. Many of the few conifers species that do survive are super-abundant.

"In the northern hemisphere conifers rule the vast boreal and much of the temperate zone," says Brodribb. He adds that the angiosperms have not become ecologically dominant in many of these regions. This might be because the soils there are too poor for them to establish a nutritional advantage, in keeping with Berendse's ideas, or perhaps it's because temperatures drop too low for them to survive. But why even in 350,000 attempts the angiosperms haven't come up with species that can overcome these problems and outcompete those northern conifers is another unsolved mystery.

In the northern hemisphere conifers rule

Today's plant scientists understandably have a better handle on the origins of flowering plants than Darwin did, but they are still struggling to explain the group's diversity, and why despite this it has failed to become dominant in some parts of the world.

Augusto, at least, is confident that answers will eventually be found, in part because these mysteries continue to fascinate researchers. And while there is little doubt this fascination stems in part from the ecological and economic importance of angiosperms today, perhaps it is also partly down to Darwin and his way with words. "I think the 'abominable mystery' quote does contribute to the general interest in angiosperms," adds Augusto.


7 Reasons Why Plants Are Valuable and Important

There are 7 reasons why plants are valuable and important. Everyday, we encounter plants whether it is in parks, the wild outbacks of nature, or in the simple pleasure of plantscaping the inside and outside of our homes. But do we truly understand the vital role plants have in this world? The very thought should cause us to pay more attention to the beautiful botany that surrounds us.

7 Reasons Why Plants are Valuable and Important

FOOD The sun is provider of all energy. We eat plants to gather the energy stored in their cells. And we are here because our ancestors foraged plants for food. They learned the ways of agriculture to make it easier and grew plants that produced products such as wheat and corn to eat. Approximately 7,000 different plant species have been cultivated and used as food for people. Though humans can live on the consumption of animal products, it is just a step away from plants since cows, pigs, sheep, chickens, rabbits and other animals eat plants to live.

AIR The air we breath mainly consists of 78% nitrogen and 21% oxygen. But it is oxygen that is vital for our cells to produce energy, energy that originated with the sun. When the sun shines down, plants absorb the sunlight to produce energy and end up releasing oxygen into the air as a by-product of their metabolism. We in turn inhale the oxygen for our survival and exhale the carbon dioxides plants require. Breath deeply and drink in the oxygen-laden air and realize it’s because of plants we are alive.

WATER Where there is water, there is life. Plants regulate the water cycle by distributing and purifying the planet’s water supply. Through the act of transpiration, plants move the water from the soil up their roots and out into the atmosphere. Moisture accumulates into clouds and eventually the water droplets are returned back down as rain to revitalize life on earth.

MEDICINE Many of prescription medicines come from plant extracts or synthesized plant compounds. Aspirin comes from the bark of the willow. Mint leaves have mentha that is used in throat lozenges, muscle creams and nasal medicine. The malaria drug ingredient quinine is from
the bark of the Cinchona tree. About 65% – 80% of the world’s population use holistic plant-based medicine as their primary form of healthcare according to the World Health Organization.

WELLNESS The implementation of LEED and WELL Building Standard shows that society is learning the value of incorporating nature or biophilia into man-made environments, both inside and outside for psychological and physical health. Plants advance health, happiness, mindfulness and productivity when weaved inside buildings and throughout the communities. Including living plants inside a home or business revitalizes the air, humidity and lowers stress levels for better wellness.

HABITAT and CLOTHING Plants make up the backbone of earth’s diverse landscape that provide hundreds of unique habitats necessary for life. Flowers dance in the fields while grasses on a hill sway in the wind. Trees strut tall in their habitat and act as the earth’s dynamic lungs, powering life everywhere. Birds pick up straw, leaves, bark, along with feathers, hairs and other items to make a comfy nest in a tree, bush or even tall grasses. Our ancestors used thatched roofs made of grasses or palm fronds, and wood to secure their homes. Industrial hemp was one of the first plants to be spun into usable fiber 10,000 years ago. Plants in all their diversity keep the cycle of life moving.

CLIMATE Excessive carbon released into the environment has been blamed for the current climate change we are experiencing. But rarely is it explained that plants store carbon by pulling it from the air. Plants help keep much of the carbon dioxide produced from our burning of fossils fuels out of the atmosphere. We owe our temperate climate to the perpetual landscape of green that blankets our world.


Dual roles: Conflict and the evolution of flower form

An alternative approach to understanding the ecological forces that maintain variation in flower size and form within plant populations follows from two fundamental observations on floral biology. First, flowers and the organs that compose them fulfill a number of ecological functions over their lifetimes. Whereas attracting pollinators is clearly a part of the “job description” for flowers of animal-pollinated plants, other, possibly conflicting functions are well known. For example, Grant (1950) and Stebbins (1970) both described the evolution of flower form as a process of adaptive compromise between effective pollination and ovule protection. Historically, these conflicting functions have been assigned to different flower parts, with the calyx, or sepals, accorded a major role in protection and the corolla, or petals, the major attractive role.

It turns out, however, that plants are seldom so tidy. In paintbrushes (Castilleja spp.), flower bracts have the major attractive function. In the rose family, fusion of calyx, corolla, and stamen bases gives rise to the hypanthium, an organ that surrounds the ovaries and is thought to protect them from herbivory ( Grant 1950, Simpson 1998). In grapes, the corolla encloses and protects the developing bud but is shed as the flower opens. In grasses, the entire perianth (i.e., petals and sepals collectively) is modified to form the lodicule, a knoblike organ that aids in flower expansion.

These examples show that characteristics of corollas as well as calyces and other flower parts may have not only attractive functions but also defensive roles. If the abundance of flower enemies varies across a plant's habitat, then conflicting selection pressures related to floral attractiveness and defense may maintain variation in the shape and size of flowers and floral organs. I call this idea the “escape hypothesis” because it postulates that natural selection for escape from enemies plays a role in floral evolution. Such enemies include disparate kinds of visitors, such as nectar or pollen robbers, flower herbivores, ovule predators, and fungal parasites.

A second aspect of floral biology is the inherent resource cost of flowers to the plant. Floral organs draw carbon, nutrients, and water from the vegetative portion of the plant, not only during their initial growth and expansion, but continuously over the flower's life span. In extremely resource limited environments, resource allocation to floral display can be costly in terms of future growth and survival. For example, in Agave deserti, a succulent plant of desert habitats, diversion of water from leaves to inflorescences during flowering contributes to the death of the vegetative plant after a single episode of reproduction ( Nobel 1977).

Even under less extreme conditions, flowers of different sizes or shapes vary in resource cost such costs may affect plant reproductive success. For example, in Sidalcea oregana, corollas account for 40% of nitrogen budgeted to reproduction ( Ashman 1994). This species exhibits gynodioecy, a sex polymorphism in which females and hermaphrodites coexist within populations. In S. oregana, flowers of hermaphrodites are larger than those of females. Because of their larger flowers, absolute nitrogen investment by hermaphrodites in corollas is greater than that by females, even though plants of the two morphs allocate similar proportions of nitrogen to flower production ( Stanton and Galloway 1990, Ashman 1994). Moreover, the two morphs differ in the amount of nitrogen that can be recovered from senescing corollas and used for other functions after flowering. On average, more than twice as much nitrogen is recovered from the corollas of small-flowered female plants than from the corollas of larger-flowered hermaphrodites ( Ashman 1994, see also Hemborg 1998). It follows that hermaphrodites experience a dual cost of corolla size compared to females, first in initial nitrogen investment and second in the amount of recoverable nitrogen.

Although in this article I focus primarily on variation in flower size within plant populations, it is possible that the shape as well as the size of flowers affects their cost in terms of limited resources. For example, tubular flowers may allow for greater light interception by subtending bracts or leaves than more rotate, or saucer-shaped, flowers. When the flower shape or size that optimizes pollinator attractiveness differs from the shape or size that optimizes resource economy, conflicting selection pressures may favor divergence in flower form within populations in relation to underlying variation in resource availability among micro-habitats or across habitat gradients. I refer to this idea as the “resource-cost hypothesis.”


RESULTS

We recorded 32 305 plant–pollinator interactions. The number of interactions recorded in each community ranged from 3505 (CA) to 13673 (CO) ( Supplementary Data Table S2 ). Mean number of interactions per population was 206 in CA (range 43–1454), 297 in CO (range 42–1911), 364 in GA (range 26–1730) and 307 in PA (range 31–1359). Overall, 88·5 % of the populations surveyed had more than 50 recorded interactions. Most of the pollinators recorded were bees, accounting for 48·9 % of the flower visits. The second most frequent group was coleopterans (21·5 % of the interactions), followed by ants (14·7 %), dipterans (8·8 %), lepidopterans (3·5 %) and wasps (2·5 %). Bees and coleopterans were the two most abundant groups in all four communities, except CA, which was largely dominated by ants ( Table S2 ).

The four communities showed a high degree of similarity in flower colours. The most common floral colour in the four communities was lilac–pink (30–50 % of the species), followed by white (16–29 %) ( Table S1 ). UV–yellow flowers were also well represented (14–24 %), although they were lacking in GA. Yellow (12–15 %), purple (4–9 %) and green (4–6 %) flowers were less frequent. The association between colour categories and pollinator composition is shown in Supplementary Data Table S3 .

Phylogenetic signal of colour variables

All colour descriptors considered showed significant phylogenetic signal when the four communities were pooled ( Table 2). In most cases, however, significance was lost when the communities were analysed separately, possibly due to small sample sizes. In all cases, K and Kmult values were <1, indicating that related species were less similar than expected under the Brownian motion evolution model.

Analyses of phylogenetic signal for colour descriptors brightness, chroma, hue (Blomberg’s K values) and colour composition (Kmult values) in the four study communities separately and lumped together. Significant results (P < 0·05) in bold

Community . Number of species . Brightness . Chroma . Hue . Colour composition .
CA 17 0·73 0·780·85 0·48
CO 46 0·35 0·570·710·33
GA 25 0·26 0·61 0·44 0·25
PA 21 0·34 0·520·76 0·26
CA+CO+GA+PA 85 0·570·600·710·38
Community . Number of species . Brightness . Chroma . Hue . Colour composition .
CA 17 0·73 0·780·85 0·48
CO 46 0·35 0·570·710·33
GA 25 0·26 0·61 0·44 0·25
PA 21 0·34 0·520·76 0·26
CA+CO+GA+PA 85 0·570·600·710·38

Analyses of phylogenetic signal for colour descriptors brightness, chroma, hue (Blomberg’s K values) and colour composition (Kmult values) in the four study communities separately and lumped together. Significant results (P < 0·05) in bold

Community . Number of species . Brightness . Chroma . Hue . Colour composition .
CA 17 0·73 0·780·85 0·48
CO 46 0·35 0·570·710·33
GA 25 0·26 0·61 0·44 0·25
PA 21 0·34 0·520·76 0·26
CA+CO+GA+PA 85 0·570·600·710·38
Community . Number of species . Brightness . Chroma . Hue . Colour composition .
CA 17 0·73 0·780·85 0·48
CO 46 0·35 0·570·710·33
GA 25 0·26 0·61 0·44 0·25
PA 21 0·34 0·520·76 0·26
CA+CO+GA+PA 85 0·570·600·710·38

Association between pollinator groups and regions of the colour spectrum

The CCAs revealed clear associations between certain pollinator groups and certain colours ( Figs 1 and 2). Visual inspection of the resulting biplots revealed that some of these patterns were relatively consistent across the four communities ( Fig. 1, Table 3).

CCA biplots of pollinator groups and bands of the colour spectrum (coloured squares) corresponding to UV, blue, yellow and red in each of the four communities (CA, CO, GA, PA). Each dot represents a plant population and dot colours correspond to the flower colour categories shown in the legend (for example spectra of each category, see Table S1 ). BEE, bees ANT, ants WAS, wasps DIP, dipterans COL, coleopterans LEP, lepidopterans.

CCA biplots of pollinator groups and bands of the colour spectrum (coloured squares) corresponding to UV, blue, yellow and red in each of the four communities (CA, CO, GA, PA). Each dot represents a plant population and dot colours correspond to the flower colour categories shown in the legend (for example spectra of each category, see Table S1 ). BEE, bees ANT, ants WAS, wasps DIP, dipterans COL, coleopterans LEP, lepidopterans.

CCA biplot of pollinator groups and bands of the colour spectrum (coloured squares) corresponding to UV, blue, yellow and red (data from the four communities lumped together). Each dot represents a plant population and dot colours correspond to the flower colour categories shown in the legend (for example spectra of each category, see Table S1 ). BEE, bees ANT, ants WAS, wasps DIP, dipterans COL, coleopterans LEP, lepidopterans.

CCA biplot of pollinator groups and bands of the colour spectrum (coloured squares) corresponding to UV, blue, yellow and red (data from the four communities lumped together). Each dot represents a plant population and dot colours correspond to the flower colour categories shown in the legend (for example spectra of each category, see Table S1 ). BEE, bees ANT, ants WAS, wasps DIP, dipterans COL, coleopterans LEP, lepidopterans.

R values of phylogenetically controlled partial Mantel tests between colour descriptors and pollinator composition in the four communities and overall (data of the four communities lumped together). All results are non-significant

Community . Brightness . Chroma . Hue . Colour composition .
CA −0.089 0.096 0.199 0.158
CO −0.002 −0.031 0.015 −0.080
GA −0.025 0.115 −0.082 −0.038
PA −0.103 −0.063 −0.035 0.051
Overall 0.021 −0.023 0.019 0.006
Community . Brightness . Chroma . Hue . Colour composition .
CA −0.089 0.096 0.199 0.158
CO −0.002 −0.031 0.015 −0.080
GA −0.025 0.115 −0.082 −0.038
PA −0.103 −0.063 −0.035 0.051
Overall 0.021 −0.023 0.019 0.006

R values of phylogenetically controlled partial Mantel tests between colour descriptors and pollinator composition in the four communities and overall (data of the four communities lumped together). All results are non-significant

Community . Brightness . Chroma . Hue . Colour composition .
CA −0.089 0.096 0.199 0.158
CO −0.002 −0.031 0.015 −0.080
GA −0.025 0.115 −0.082 −0.038
PA −0.103 −0.063 −0.035 0.051
Overall 0.021 −0.023 0.019 0.006
Community . Brightness . Chroma . Hue . Colour composition .
CA −0.089 0.096 0.199 0.158
CO −0.002 −0.031 0.015 −0.080
GA −0.025 0.115 −0.082 −0.038
PA −0.103 −0.063 −0.035 0.051
Overall 0.021 −0.023 0.019 0.006

Overall, bees were associated with purple flowers and ants with UV–yellow and green flowers. Wasps and dipterans were mostly associated with UV–yellow flowers. Coleopterans were associated with white and yellow flowers and lepidopterans with pink flowers ( Table 4, Fig. 2).

Relationships between pollinator groups and the different floral colours in the four communities and overall (data of the four communities lumped together) estimated visually from the CCA biplots of Fig. 1 for the four communities and Fig. 2 for overall tendencies

Relationships between pollinator groups and the different floral colours in the four communities and overall (data of the four communities lumped together) estimated visually from the CCA biplots of Fig. 1 for the four communities and Fig. 2 for overall tendencies

Relationship between flower colour and pollinator assemblages

Results from the partial Mantel test showed no significant association between flower colour and pollinator assemblages ( Table 4). Plants with similar colour descriptors, including colour composition, did not attract similar pollinator assemblages in any of the communities, and similar results were obtained when data from the four communities were lumped together.


Americans don't just like jeans to be skinny

Obesity in America reached an all time high in 2016, yet Americans are still aspiring to be thin. According to Dr. Mairi Macleod, a researcher in the School of Psychology at the University of Dundee, this dilemma directly leads to body dissatisfaction.

Much of how we view ourselves and others can be linked back to the media. In a study conducted by Lynda Boothroyd of the University of Durham, young women were shown many pictures of overweight or underweight women. Interestingly, the women rated the attractiveness according to what they were seeing, not solely based on their predetermined set of ideals. For example, if shown photos of underweight women, the women would consider thin to be most attractive.

People in places without access to the media, like the remote parts of Nicaragua, don't think as much about being overweight. Well, they didn't until they were gifted — or cursed — with western media. As part of another study, Boothroyd observed what happened when villagers began watching our TV shows. Sure enough, they started idealizing thinner bodies and some even tried to lose weight.


Can You Make Yourself More Attractive?

Research shows that there may be a few things you can do to improve your chances of attracting the person you want most, although your results may vary.

Be Comfortable and Confident.

Developing more comfort in your own body can greatly increase your dynamic attractiveness. Take a dance class, or just spend more time dancing around your living room. Join a running club or take up acting. And improve your dynamic attractiveness by using open, expansive body gestures. Similarly, when you focus on your strengths and seek out the environments where you're most confident, you'll feel more secure, which can translate into appearing more attractive to others.

Network

Finding love at a bar happens less often than you think, University of California, Davis psychologist Paul Eastwick says. A better plan is to join an activity group where you'll meet new people who share your interests. "If you keep moving through those networks, you'll eventually get to know people you click with," he says. "People are good at this when it comes to finding a job. Maybe it seems instrumental or creepy for dating, but I do think there is a way to leverage your network."

Answer the 36 Questions.

Go online and download the classic intimacy-boosting questionnaire, "The Experimental Generation of Interpersonal Closeness: A Procedure and Some Preliminary Findings." Then invite the person you're interested in to sit down and run through some of them with you.

Don't Play (Too) Hard to Get.

Yes, you may not want to seem easy, but you also don't want to make it so hard to win you that a potential partner gives up. "There is old research showing that playing hard-to-get, even after initial attraction, is not a good idea," State University of New York at Stony Brook psychologist Arthur Aron says. "The ideal is to make it feel as if it's hard for everyone else to get you. We like challenges, but we like challenges we can win."

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Psychologists find smiling really can make people happier

Smiling really can make people feel happier, according to a new paper published in Psychological Bulletin.

Coauthored by researchers at the University of Tennessee, Knoxville and Texas A&M, the paper looked at nearly 50 years of data testing whether facial expressions can lead people to feel the emotions related to those expressions.

"Conventional wisdom tells us that we can feel a little happier if we simply smile. Or that we can get ourselves in a more serious mood if we scowl," said Nicholas Coles, UT PhD student in social psychology and lead researcher on the paper. "But psychologists have actually disagreed about this idea for over 100 years."

These disagreements became more pronounced in 2016, when 17 teams of researchers failed to replicate a well-known experiment demonstrating that the physical act of smiling can make people feel happier.

"Some studies have not found evidence that facial expressions can influence emotional feelings," Coles said. "But we can't focus on the results of any one study. Psychologists have been testing this idea since the early 1970s, so we wanted to look at all the evidence."

Using a statistical technique called meta-analysis, Coles and his team combined data from 138 studies testing more than 11,000 participants from all around the world. According to the results of the meta-analysis, facial expressions have a small impact on feelings. For example, smiling makes people feel happier, scowling makes them feel angrier, and frowning makes them feel sadder.

"We don't think that people can smile their way to happiness," Coles said. "But these findings are exciting because they provide a clue about how the mind and the body interact to shape our conscious experience of emotion. We still have a lot to learn about these facial feedback effects, but this meta-analysis put us a little closer to understanding how emotions work."


Facial Symmetry and Attractiveness

One of the leading aspects used to measure conventional attractiveness scientifically is facial symmetry. Typically, this is measured by manipulating an original photo of a person (we are all at least a little asymmetric, no person is perfectly symmetrical) into a perfectly symmetric version of their face. This manipulated, symmetric image is then presented to test subject along with the original photo. Subjects are then asked to indicate which face is more attractive, usually indicating the symmetrical version. (These findings have been replicated in multiple studies.) Though these results indicate that people prefer and perceive the more symmetric faces as attractive, there has been considerable debate about why this is.

There have been two theories of substance proposed by researchers to explain the preference for symmetrical faces:

The Evolutionary Advantage theory proposed that symmetrical faces are perceived as more attractive because the symmetry indicates good health in an individual. Everyone’s genes are designed to develop a face perfectly symmetrical, but as we grow, develop, and then age, disease, infections, and parasites cause imperfection in our appearance (asymmetry). Thus, those that have less asymmetry and imperfections, are perceived as having better and stronger immune systems to withstand the infections and parasites that occur naturally. So, symmetry is a good indicator of a person having good genes to pass on their offspring. Under the Evolutionary Advantage view of symmetric preferences, we have evolved to prefer symmetry and perceive it as attractive because over human history we have consistently and constantly preferred healthier individuals for mates. In sum, the Evolutionary Advantage view suggests that attraction to symmetric individuals reflects an attraction to healthy individuals who would be good mates.

The second theory to explain the preference for facial symmetry is Perceptual Bias. This theory suggests that the human visual system may be “hard wired” in a way that makes it much easier to process symmetrical stimuli than asymmetrical stimuli. If this is true, the ease of processing symmetrical stimuli would cause us to naturally prefer them to asymmetrical stimuli. Under this view, preferences for symmetrical faces would be no different than for any other object. So according to this, as well as preferring symmetrical faces, humans would also prefer more symmetrical objects of any kind. This has been supported as it has been found that people much prefer symmetrical pieces of abstract art and sculptures to asymmetrical ones.

Little and Jones (2003) did a study to investigate why people prefer symmetric faces to asymmetric ones, by testing and attempting to apply predictions from both the Evolutionary Advantage theory and Perceptual Bias. Previous studies found that the symmetric preference is stronger for attractiveness of opposite sex than same sex. Little and Jones found that the manipulated, symmetric faces were judged more attractive when shown the right way up, but not when the faces were inverted. These findings suggest that symmetry is more important in mate choice stimuli than in other stimuli, supporting the Evolutionary Advantage theory and presenting multiple difficulties for the Perception Bias theory (if symmetry of any kind was preferred then the more symmetrical face would have been indicated as more attractive both the right way up AND when inverted).

If anyone is interested in learning more, you can benefit from taking a class or just researching Penn State’s very own Dr. Mark Shriver, a geneticist, who conducts research in Brazil on facial symmetry. Though ongoing, Shriver’s research has measured thousands of Brazilian (and other ethnicities) faces in facial symmetry, judging their scientific attractiveness and therefore contributing the most evidence towards the idea that mixed race people are more attractive — in this case attraction is not subjective, it is purely measure with symmetry. Shriver teaches many higher level ANTH classes, but if anyone is interested, I suggest starting with ANTH 021 – Biological Anthropology.


Why Do We Get So Much Pleasure From Symmetry?

A pair of synchronized divers. The wings on a butterfly. The vaulted ceiling of a cathedral. These are some of the things that most people find visually very pleasing. But why? The answer has to do with symmetry.

Most objects in the real world are symmetrical. This is particularly true of nature: the radial symmetry of starfish or flower petals, the symmetrical efficiency of a hexagonal honeycomb, or the uniquely symmetrical crystal patterns of a snowflake. In fact asymmetry is often a sign of illness or danger in the natural world.

And, of course, human beings are symmetrical, at least on the outside (some internal organs like the heart and liver are off-center). Decades of research into sexual attraction have proven that both men and women find symmetrical faces sexier than asymmetrical ones. The leading explanation is that physical symmetry is an outward sign of good health, although large-scale studies have shown no significant health differences in people with symmetrical or asymmetrical faces. (Since severe physical asymmetries are strong indicators of genetic disorders, our brains might just be overreacting.)

The simple explanation for our attraction to symmetry is that it's familiar. Symmetrical objects and images play by the rules that our brains are programmed to recognize easily.

"I would claim that symmetry represents order, and we crave order in this strange universe we find ourselves in," writes physicist Alan Lightman in "The Accidental Universe: The World You Thought You Knew." "The search for symmetry, and the emotional pleasure we derive when we find it, must help us make sense of the world around us, just as we find satisfaction in the repetition of the seasons and the reliability of friendships. Symmetry is also economy. Symmetry is simplicity. Symmetry is elegance."

A more esoteric explanation for the satisfaction we feel at seeing a creatively symmetrical work of art, or a perfectly stacked display of soup cans in the grocery store, is that the "stuff" of our brains is inseparable from the "stuff" of nature. The neurons and synapses in our brain, and the processes by which they communicate, connect and conjure thoughts, evolved in parallel to the stars and the starfish. If nature is symmetrical, then so is our mind.

"The architecture of our brains was born from the same trial and error, the same energy principles, the same pure mathematics that happens in flowers and jellyfish and Higgs particles," writes Lightman.

Take a look at the image above. What do you see?

If you're lucky enough to have two functioning eyes and an undamaged brain, you'll say, "a bright white triangle on top of another triangle." But look closer and you'll discover that it's all an optical illusion -- there's no bright white triangle at all, just empty space surrounded by three Pac-Man look-alikes and some floating V's.

The visual trick, called the Kanizsa triangle, is so powerful that your brain fills in border lines separating the two triangles and makes the top one look brighter, even though the white spaces throughout the image are in fact the identical shade of white. Don't believe us? Cover up sections of the image with your hand and watch as the lines and color differences disappear.

So what the heck is happening?

"The brain doesn't like things that are accidental," says Mary Peterson, psychology professor and director of the Visual Perception Laboratory at the University of Arizona. "The brain creates that whiter-than-white triangle because it would be accidental that those three Pac-Men would be aligned in such a way if they were not being occluded by a white triangle."

The triangle illusion is a classic example of what's known as Gestalt psychology, named after an influential school of visual perception born in Germany in the 1920s. The famous (and famously mistranslated) Gestalt motto is: "The whole is other than the sum of its parts" (not "The whole is greater than the sum of its parts.") In other words, if our perception consisted only of adding up the details of an image, then we'd look at the above image and say, "I see three Pac-Men and some V's." But our brain is more than a calculator. It's primed to recognize signs of order in the "accidental" chaos, and to follow certain rules or shortcuts to make sense of the world.

Symmetry is one of those shortcuts. As Peterson explains, we either learn or are born with certain "priors" or shortcuts that help our brains quickly determine that we're looking at an object.

Johan Wagemans is an experimental psychologist from Belgium who specializes in visual perception and how our brains organize the constant incoming flow of information. He agrees that symmetry is not just a design principle of the outside world.

"You can also see symmetry as one of these major principles driving the self-organization of the brain," says Wagemans. "All these tendencies towards good organization and simple organization are also principles of symmetry in the dynamics of the brain itself."

But on the other hand, too much symmetry can be a tad boring. Wagemans found that while perfectly symmetrical designs are more pleasing to the brain, they're not necessarily more beautiful. Both art novices and experts prefer art that strikes an "optimal level of stimulation," says Wagemans. "Not too complex, not too simple, not too chaotic and not too orderly." Indeed, the Japanese have an aesthetic principle called fukinsei, which is all about creating balance in a composition, using asymmetry or irregularity.

Studies have shown that babies as young as 4 months have a preference for vertical symmetry over horizontal symmetry or asymmetry.