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Memes tagged “evolution”

261–280 of 312

Many Hypotheses Become Theories

The distinction between the two dictionary meanings of 'theory' is not an unbridgeable chasm, as many historical examples show. In the history of science, theorums often start off as 'mere' hypotheses. Like the theory of continental drift, an idea may even begin its career mired in ridicule, before progressing by…

Neoteny in Humans

...the concept of "neoteny"—the retention of juvenile features into adult life. It is a commonplace of human evolution that the transition from Australopithecus to Homo and from Homo habilis to Homo erectus and thence to Homo sapiens all involved prolonging and slowing the development of the body so that it still…

The Waist-to-Hip Ratio

Why does the waist-to-hip ratio matter? Singh observes that a "gynoid" fat distribution—more fat on the hips, less on the torso—is necessary for the hormonal changes associated with female fertility. An "android" fat distribution-—fat on the belly, thin hips—is associated with the symptoms of male disabilities such as…

Humans are a Self-Domesticated Animal

Mankind is a self-domesticated animal; a mammal; an ape; a social ape; an ape in which the male takes the initiative in courtship and females usually leave the society of their birth; an ape in which men are predators, women herbivorous foragers; an ape in which males are relatively hierarchical, females relatively…

Human Pairs Must Keep Each Other Interested

Likewise, the manner in which sexual selection capriciously seizes upon preexisting perceptual biases fits with the fact that apes are by nature naturally "curious, playful, easily bored, and appreciative of simulation." Miller suggests that to keep a husbanc around long enough to help in raising children, women would…

Genes versus Hormones in Homosexuality

It is clear, however, that the cause of homosexuality lies in some unusual balance of hormonal influence in the womb but not later on, a fact that further supports the idea that the mentality of sexual preference is affected by prenatal sex hormones. This is not incompatible with the growing evidence that…

Hormones on the Brain

At school, boys are fidgety, difficult, inattentive, and slow to learn, compared to girls. Nineteen out of every twenty hyperactive children are boys. Four times as many boys as girls are dyslexic and learning disabled. "Education is almost a conspiracy against the aptitudes and inclinations of a schoolboy," wrote…

How Testosterone Affects the Brain

We last met the steroid hormone testosterone in fish and birds where it was rendering them more vulnerable to parasites by exaggerating their sexual ornaments. In recent years more and more evidence has been found that testosterone affects not just ornaments and bodies but also brains. Testosterone is an ancient…

Brain Differences Between the Genders

There are three reasons to expect evolution to have produced different mentalities in men and women. The first is that men and women are mammals, and all mammals show sexual differences in behavior. As Charles Darwin put it, "No one disputes that the bull differs in disposition from the cow, the wild boar from the…

The Temple of Nature

Birth after birth the line unchanging runs, And fathers live transmitted in their sons; Each passing year beholds the unvarying kinds, The same their manners, and the same their minds. Till, as erelong successive buds decay, And insect-shoals successive pass away, Increasing wants the pregnant parent vex With the fond…

Reproduction is the Most Important Evolutionary Trait

Those strains that reproduce persist; those that do not reproduce die out. The ability to reproduce is what makes living things different from rocks. Besides, there is nothing inconsistent with free will or even chastity in this view of life. Human beings, I believe, thrive according to their ability to take…

A lot happens in 100k Years of Evolution

Inside my skull is a brain that was designed to exploit the conditions of an African savanna between 3 million and 100,000 years ago. When my ancestors moved into Europe (I am a white European by descent) about 100,000 years ago, they quickly evolved a set of physiological features to suit the sunless climate of…

Hummingbirds are Proof of the Cost of Sex

If sex had no cost, hummingbirds would not exist. Hummingbirds eat nectar, which is produced by flowers to lure pollinating insects and birds. Nectar is a pure gift by the plant of its hard-won sugar to the hummingbird, a gift given only because the hummingbird will then carry pollen to another plant. To have sex with…

The Tangled Bank Theory

Michael Ghiselin developed this idea further in 1974 and made some telling analogies with economic trends. As Ghiselin put it, "In a saturated economy, it pays to diversify." Ghiselin suggested that most creatures compete with their brothers and sisters, so if everybody is a little different from their brothers and…

The Immune System VS Viruses

The immune system consists of white blood cells that come in about 10 million different types. Each type has a protein lock on it called an "antibody," which corresponds to a key carried by a bacterium called an "antigen." If a key enters that lock, the white cell starts multiplying ferociously in order to produce an…

Cooperation VS Capitalism

Finding the right balance between cooperation and competition has been the goal and bane of Western politics for centuries. Adam Smith recognized that the economic needs of the individual are better met by unleashing the ambitions of all individuals than by planning to meet those needs in advance. But even Adam Smith…

Environment of Evolutionary Adaptedness

Then for more than a million years people lived in a way that couldn't have changed much. They inhabited grasslands and woodland savannas, first in Africa, later in Eurasia, and eventually in Australasia and the Americas. They hunted animals for food, gathered fruits and seeds, and were highly social within each tribe…

If Humans Were Like Chimpanzees

If we were hairless chimpanzees, our society would still Dok fairly familiar in some ways. We would live in families, be very social, hierarchical, group-territorial, and aggressive toward other groups than those we belong to. In other words, we would be family-based, urban, class-conscious, nationalist, and…

If Humans were Like Sparrows

It is my contention that man is just like an ibis or a swallow or a sparrow in several key respects. He lives in large colonies. Males compete with one another for places in a pecking order. Most males are monogamous. Polygamy is prevented by wives who resent sharing their husbands lest they also share his…

Orgasms and Sperm Retention

t. Baker and Bellis discovered that the amount of sperm that is retained in a woman's vagina after sex varies according to whether she had an orgasm and when. It also depends on how long it was since she last had sex: The longer the period, the more sperm stays in, unless she has what the scientists call "a…