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Posts Tagged ‘Evolution’

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For a period of 2 million years, ending with the last ice age around 10,000 B.C., the Earth experienced a series of convulsive glacial events. This rapid-fire climate change meant that humans couldn’t rely on consistent patterns to know which animals to hunt, which plants to gather, or even which predators might be waiting around the corner. How did we cope? By getting smarter. The neuro­physi­ol­ogist William Calvin argues persuasively that modern human cognition—including sophisticated language and the capacity to plan ahead—evolved in response to the demands of this long age of turbulence.

On the scale of time used in evolution, the advancement of human intelligence happened at a breakneck pace. Sophisticated language is a uniquely human trait which no other creature on Earth possesses.

There are all sorts of doomsday scenarios for the coming century. Humanity survived until this point by being clever and we are likely so succeed in the future by using the same technique. The only difference is that we don’t need to rely on natural evolutionary processes to evolve greater intelligence. We use the tools we’ve created, such as the internet, to augment our intelligence to the next level.

There is concern that the nature of the internet has given people a sort of ADD, and that people are losing their skill to read long and in depth pieces of information.

With every technological step forward, though, has come anxiety about the possibility that technology harms our natural ability to think. These anxieties were given eloquent expression in these pages by Nicholas Carr, whose essay “Is Google Making Us Stupid?” (July/August 2008 Atlantic) argued that the information-dense, hyperlink-rich, spastically churning Internet medium is effectively rewiring our brains, making it harder for us to engage in deep, relaxed contemplation.

Carr’s fears about the impact of wall-to-wall connectivity on the human intellect echo cyber-theorist Linda Stone’s description of “continuous partial attention,” the modern phenomenon of having multiple activities and connections under way simultaneously. We’re becoming so accustomed to interruption that we’re starting to find focusing difficult, even when we’ve achieved a bit of quiet. It’s an induced form of ADD—a “continuous partial attention-deficit disorder,” if you will.

Not everyone agrees with that assessment.

Scientists describe these skills as our “fluid intelligence”—the ability to find meaning in confusion and to solve new problems, independent of acquired knowledge. Fluid intelligence doesn’t look much like the capacity to memorize and recite facts, the skills that people have traditionally associated with brainpower. But building it up may improve the capacity to think deeply that Carr and others fear we’re losing for good.

Read the whole thing, since there’s a lot more where that came from.

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Finding reasons why evolution would favor big brains and intelligence in humans is easy. A more difficult line of inquiry is to determine if there are costs involved in having advanced intelligence, and what they may be.

“The results from our analysis suggest that humans aren’t as efficient as chimpanzees in carrying out programmed cell death. We believe this difference may have evolved as a way to increase brain size and associated cognitive ability in humans, but the cost could be an increased propensity for cancer,” said McDonald.

This particular hypothesis indicates that increased cancer rates is one significant cost.

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Before you get all grossed out and try to blame us for losing your lunch, take a moment to ponder the seriousness of this question. At some point in our evolutionary history, it made sense for us to lose body hair. The advantage in having little or no body hair has to do with the human ability of running upright. We are actually the most energy efficient runners (next to dogs) in the animal kingdom, and one way such a thing is possible is through an efficient cooling system, via sweat. Sweating works much more effectively without fur getting in the way of course.

Now, back to our original question.

Robin Weiss, a virologist at University College London, had an intimate revelation in the shower recently.

Public hair, he decided, developed as a sexual ornament. It became bushy and prominent after our ancestors split from non-human primates, he says, when we lost most of our other body hair. As it disappeared, human pubic hair acquired a new role as a prominent sexual ornament, a visual signal of sexual maturity and possibly a reservoir for sexual pheromones.

This theory is actually supported by examining the DNA of lice, both the human and gorilla versions.

Our ancestors and those of gorillas went their separate evolutionary ways at least 7 million years ago. But the lice that infect gorillas and modern humans didn’t become different species until much later – around 3.3 million years ago, as revealed through research in 2007 by David Reed of the University of Florida Natural History Museum in Gainesville.

Reed argues that gorilla lice crossed over to humans through incidental contact, such as humans sleeping in an abandoned gorilla nest. Weiss argues that the pubic hair in humans evolved to become coarser, which gave the gorilla lice something to get a grip on.

To back up his case Weiss visited zoos to peer at the groins of our closest relatives. He noticed that in other great apes, hair in the pubic region was if anything much finer and shorter than elsewhere on the body – the opposite of the human situation. It supported his argument that human pubic hair is different and probably unique, both in its evolution and in its physical appearance and purpose.

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This is a serious question.

From an evolutionary standpoint, it might make sense for women to devote their cellular efforts to reproduction instead of developing an energy-hogging brain, Ward suggested. Females of plenty of other species make this compromise, so why not humans?

The answer is that human females with larger brains had a significant fitness advantage, probably due to the complexity of human social interaction.

Developing big brains must have helped women pass on their genes, she reasoned. One possible explanation is that these larger, more connected brains helped ancestral females navigate an increasingly social world, where gaining benefits from other humans is just as important to survival as traits that improve fitness more directly, such as a strong immune system.

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