evolution

if it moves fuck it

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In a mossy forest in the western Andes of Ecuador, a small, cocoa-brown bird with a red crown sings from a slim perch. […] Three rival birds call back in rapid response. […] They are singing with their wings, and their potential mates seem to find the sound very alluring. […]

This is an evolutionary innovation — a whole new way to sing. But the evolutionary mechanism behind this novelty is not adaptation by natural selection, in which only those who survive pass on their genes, allowing the species to become better adapted to its environment over time. Rather, it is sexual selection by mate choice, in which individuals pass on their genes only if they’re chosen as mates. From the peacock’s tail to the haunting melodies of the wood thrush, mate choice is responsible for much of the beauty in the natural world.

Most biologists believe that these mechanisms always work in concert — that sex appeal is the sign of an objectively better mate, one with better genes or in better condition. But the wing songs of the club-winged manakin provide new insights that contradict this conventional wisdom. Instead of ensuring that organisms are on an inexorable path to self-improvement, mate choice can drive a species into what I call maladaptive decadence — a decline in survival and fecundity of the entire species. It may even lead to extinction.

{ NYT | Continue reading }

art { Cy Twombly, Achilles Mourning the Death of Patroclus, 1962 }

People are afraid to merge on freeways in Los Angeles

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Most people in industrialized societies grow up in core (parents only) families with few if any siblings. Based on an evolutionary perspective, it may be argued that this environment reflects a mismatch, in that the tribal setting offered a larger number of close affiliates. The present project examined whether this mismatch may have a negative impact on mental health. […]

The number of household members correlated with scores on good mental health at all ages tested (3, 5 and 8 years). […] Living with a single mother did not make any difference compared to two parents. Girls were slightly more responsive to the presence of siblings than boys. Household pets did not have any appreciable impact.

{ BMC Psychology | Continue reading }

You’re stuck in the middle, and the pain is thunder

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The classic argument is that those of our ancestors who saw more accurately had a competitive advantage over those who saw less accurately and thus were more likely to pass on their genes that coded for those more accurate perceptions, so after thousands of generations we can be quite confident that we’re the offspring of those who saw accurately, and so we see accurately. That sounds very plausible. But I think it is utterly false. It misunderstands the fundamental fact about evolution, which is that it’s about fitness functions — mathematical functions that describe how well a given strategy achieves the goals of survival and reproduction. […]

Evolution has shaped us with perceptions that allow us to survive. But part of that involves hiding from us the stuff we don’t need to know. And that’s pretty much all of reality, whatever reality might be.

{ Quanta | Continue reading }

cloaked in the pall of the ace of spaces

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Venturing into novel terrain poses physical risks to a female and her offspring. Females have a greater tendency to avoid physical harm, while males tend to have larger range sizes and often outperform females in navigation-related tasks. Given this backdrop, we expected that females would explore a novel environment with more caution than males, and that more-cautious exploration would negatively affect navigation performance. […]

Findings support the idea that the fitness costs associated with long-distance travel may encourage females to take a more cautious approach to spatial exploration, and that this caution may partially explain the sex differences in navigation performance.

{ Human Nature | Continue reading }

When you knew that it was over were you suddenly aware that the autumn leaves were turning to the color of her hair?

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In Women After All: Sex, Evolution, and the End of Male Supremacy, Melvin Konner argues that male domination is an anomaly of human history, not a natural state for the human species. Specifically, Konner suggests that male supremacy is largely an effect of an oppressive social arrangement, namely civilization, which began with the invention of agriculture when humans began to form permanent settlements. Permanent settlements enabled men to be able to accumulate resources and allowed population densities to increase mainly through higher birth rates. Higher population densities placed more intense pressure on the land’s resources. Therefore, it became necessary for men to form coalitions with neighbors to defend against intruders. Power became concentrated in the hands of a few men, leading to a stratified society where male supremacy and female subordination reigned and male violence and war intensified. Today, Konner argues that technology limits the need for the muscle and strength of men, and male domination has outlived its purpose and is maladaptive. Therefore, empowering women is the next step in human evolution. Through empowering women, equality between the sexes will be restored and man-made disasters, such as wars, sex scandals, and financial corruption, will significantly decrease or be eliminated since women (who Konner claims are less emotional than men) will be in positions of leadership and power.

{ Evolutionary Psychology | Continue reading }

Towards a Fictionalist Philosophy of Mathematics

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We now have four good Darwinian reasons for individuals to be altruistic, generous or ‘moral’ towards each other. First, there is the special case of genetic kinship. Second, there is reciprocation: the repayment of favours given, and the giving of favours in ‘anticipation’ of payback. Following on from this there is, third, the Darwinian benefit of acquiring a reputation for generosity and kindness. And fourth, if Zahavi is right, there is the particular additional benefit of conspicuous generosity as a way of buying unfakeably authentic advertising.

{ Richard Dawkins | Continue reading }

photo { Todd Fisher }

‘Il y a dans la jalousie plus d’amour-propre que d’amour.’ –La Rochefoucauld

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A recent Norwegian study shows that men and women react differently to various types of infidelity. Whereas men are most jealous of sexual infidelity, so-called emotional infidelity is what makes women the most jealous. Evolutionary psychology may help explain why this may be. […]

Men and women over thousands of generations have had to adapt to different challenges that are related to reproduction. Infidelity is one such challenge. A man must decide whether he really is the father of his partner’s child, and if he should choose to invest all his protection and status resources on this child. Since the dawn of time men have grappled with paternity insecurity, since fertilization occurs inside a woman’s body.

According to the evolutionary psychology explanation, men’s jealousy is an emotional reaction to signs of sexual infidelity. The jealousy serves to reduce the chances that his partner is cheating, since he then monitors her more closely.

It’s a different story for the child’s mother. She knows for sure that she is the child’s mother, but she must ensure that the child’s father will provide their offspring with food and the security and social status it needs. The greatest threat for the woman is not that the man has sex with other women, but that he spends time and resources on women other than her.

{ Medical Xpress | Continue reading }

(A firm heelclacking is heard on the stairs.)

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The ratio between the body circumference at the waist and the hips (or WHR) is a secondary sexual trait that is unique to humans and is well known to influence men’s mate preferences. Because a woman’s WHR also provides information about her age, health and fertility, men’s preference concerning this physical feature may possibly be a cognitive adaptation selected in the human lineage. […]

We analyzed the WHR of women considered as ideally beautiful who were depicted in western artworks from 500 BCE to the present. These vestiges of the past feminine ideal were then compared to more recent symbols of beauty: Playboy models and winners of several Miss pageants from 1920 to 2014. We found that the ideal WHR has changed over time in western societies: it was constant during almost a millennium in antiquity (from 500 BCE to 400 CE) and has decreased from the 15th century to the present. Then, based on Playboy models and Miss pageants winners, this decrease appears to slow down or even reverse during the second half of the 20th century.

The universality of an ideal WHR is thus challenged, and historical changes in western societies could have caused these variations in men’s preferences.

{ PLOS | Continue reading }

You live and you learn

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The “hygiene hypothesis” […] suggests that people in developed countries are growing up way too clean because of a variety of trends, including the use of hand sanitizers and detergents, and spending too little time around animals.

As a result, children don’t tend to be exposed to as many bacteria and other microorganisms, and maybe that deprives their immune system of the chance to be trained to recognize microbial friend from foe.

That may make the immune system more likely to misfire and overreact in a way that leads to allergies, eczema and asthma, Hesselmar says. […]

In their latest research, the researchers took a look at how people wash their dishes. […] In families who said they mostly wash dishes by hand, significantly fewer children had eczema, and somewhat fewer had either asthma or hay fever, compared to kids from families who let machines wash their dishes.

{ NPR | Continue reading }

photo { Daria Zhemkova photographed by Mario Kroes }

Brass and reeds, brace and ready!

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A study has shown that in contemporary hunter-gatherer tribes, men and women tend to have equal influence on where their groups lives and who they live with. The findings challenge the idea that sexual equality is a recent invention, suggesting that it has been the norm for humans for most of our evolutionary history.

Mark Dyble, an anthropologist who led the study at University College London, said: “There is still this wider perception that hunter-gatherers are more macho or male-dominated. We’d argue it was only with the emergence of agriculture, when people could start to accumulate resources, that inequality emerged.” […]

Dyble said that egalitarianism may even have been one of the important factors that distinguished our ancestors from our primate cousins. “Chimpanzees live in quite aggressive, male-dominated societies with clear hierarchies,” he said. “As a result, they just don’t see enough adults in their lifetime for technologies to be sustained.”

{ Raw Story | Continue reading }

Now baby we can do it take the time, do it right, we can do it baby

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The sexual selection concept arises from the observation that many animals had evolved features whose function is not to help individuals survive, but help them to maximize their reproductive success. This can be realized in two different ways:

• by making themselves attractive to the opposite sex (intersexual selection, between the sexes), or
• by intimidating, deterring or defeating same-sex rivals (intrasexual selection, within a given sex).

Thus, sexual selection takes two major forms: intersexual selection (also known as ‘mate choice’ or ‘female choice’) in which males compete with each other to be chosen by females; and intrasexual selection (also known as ‘male–male competition’) in which members of the less limited sex (typically males) compete aggressively among themselves for access to the limiting sex. The limiting sex is the sex which has the higher parental investment, which therefore faces the most pressure to make a good mate decision.

For intersexual selection to work, one sex must evolve a feature alluring to the opposite sex, sometimes resulting in a “fashion fad” of intense selection in an arbitrary direction. Or, in the second case, while natural selection can help animals develop ways of killing or escaping from other species, intrasexual selection drives the selection of attributes that allow alpha males to dominate their own breeding partners and rivals.

{ Wikipedia | Continue reading }

Canine teeth, horns, claws, and the sheer size and strength of certain male animals provide strong examples of physical weapons, and aggression is a behavioral weapon among humans and other animals. A peacock’s tail, which is useless and costly to sustain, is the most famous example of an ornament. Showing off and creativity may be the human equivalents of this ornamentation. Certain polygynous species, such as the elephant seal, become weapon specialists, relying primarily on intrasexual combat to achieve reproductive success. Other species, such as the peacock and numerous birds of paradise, specialize in intersexual selection to produce extravagant male ornaments. Humans are versatile animals who rely on a large brain to facilitate amassing and facultatively employing a large repertoire of survival and reproductive strategies, including weapons and ornaments.

Even though ancestral men may have used intrasexual combat more than intersexual ornaments in acquiring mates and much human female choice may also have derived from male contests, modern men use both intrasexual and intersexual mating strategies as evidenced by much research showing a clear association between mating motivation and various behaviors that constitute weapons and ornaments in men. Specific weapon-like behaviors under mating investigation include physical or direct aggression in response to provocation, social dominance and status, endorsing warring attitudes, and producing a low voice pitch. The studied ornament-like behaviors include conspicuous material consumption, risk taking, humor, being unique and non-conforming, becoming loss averse, making generous financial donations, and exhibiting heroic altruism, all of which are preferred by women.

These studies suggest that, similar to other male animals, men can exhibit weapon-like and ornament-like behaviors, but, unlike many male animals that specialize in either weapons or ornaments nearly to the exclusion of the other, men seem to have developed the versatility to acquire and apply both strategies to facultatively respond to intrasexual and intersexual competition. Men may use weapons and ornaments facultatively as situational responses to intersexual and intrasexual conditions and, over time, may also develop behavioral tendencies in using one strategy more frequently over the other, adding to the vast individual differences along a weapon-ornament dimension.

{ Evolutionary Psychology | PDF }

photo { Jerry Schatzberg }

‘Why are there beings at all, and why not rather nothing?’ –Heidegger

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Imagine a virus wipes out everyone on the planet except [a man]. […] He finds the last woman on Earth. […] Can they repopulate the Earth? To do so, their children would have to mate with one another, or mom and dad, in order to rebuild the human race. All the incestuous taboos aside, is this even genetically possible?

Inbreeding has unfortunate genetic consequences due to the increased inheritance of recessive genes, which can result in neonatal death. Inbred children that survive are at increased risk of congenital birth defects, reduced fertility, smaller size, immune deficiencies, cystic fibrosis, and more. These defects are also likely to be passed on to their children as well. […]

Some real-life examples of the consequences of inbreeding can be found in places where there are restricted breeding opportunities — for example, within monarchies, islanders, or closed societies. Hemophilia was notoriously prevalent in European royal families. Some Amish societies have a larger number of children born with extra digits on their hands or feet. Jews of Eastern European descent tend to have higher rates of a number of genetic diseases, including cystic fibrosis. […]

The net result of inbreeding is that the resulting population loses a diverse genetic portfolio, which means they are less resistant to rare diseases and deformities. The smaller the gene pool, the faster it gets dirty. Such individuals would also have less diverse immune systems, making it much easier for a single germ to wipe them all out. […]

In addition to the genetic landmines, the family would likely have a very difficult time overcoming the innate resistance most species have against inbreeding. Evolution knows that inbreeding is not good for the species, so it engineered a built-in “incest taboo” that creates a strong aversion to such behavior. A devil’s advocate, however, could argue that the biological barrier to familial sex could be overcome through artificial insemination.

What about using a sperm bank? Sperm is stored in liquid nitrogen, so it would stay frozen for a short time after the power goes out. However, you’d have to act fast because no one is around to monitor the storage tanks and top off the liquid nitrogen as it evaporates.

There are practical concerns to consider as well. The last man and woman, as well as their kids, would need to have large numbers of children and, unless one of the founders happens to be a doctor, it is hard to imagine many of these babies surviving in such a world. Even if they (and mom) survive childbirth, there are countless opportunities for them to perish in this type of environment before reaching childrearing age.

{ The Scope | Continue reading }

art { Hilo Chen, Beach 166, 2010 }