Chimps more like humans than apes

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Chimps more like humans than apes

 

Source > http://www.msnbc.msn.com/id/10994885/

 

DNA analysis also shows they're evolving faster than

humans

chimp family group at Australian zoo

A female chimpanzee yawns as two others nod off at the

Taronga Zoo in Sydney, Australia. A new study finds

that chimps are evolving faster than humans.

Rob Elliott / AFP / Getty Images

 

While you might think of yourself as smarter than the

average ape, beware: Those distant relatives of ours

have a knack for evolving more quickly than we do. And

by revealing this through DNA analysis, scientists

have provided support for a controversial hypothesis

that chimpanzees are more closely related to humans

than to other species of great apes with which they're

currently classified.

 

The findings were announced today in a study in the

Proceedings of the National Academy of Sciences.

 

Researchers generally agree that humans and chimps

diverged from a common ancestor about 5 million to 7

million years ago.

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Chimps are lumped with gorillas and orangutans in the

same family, Pongidae, whereas humans are in the

family Hominidae.

 

But a study in 2003 found that 99.4 percent of

important DNA sites are the same in chimps and humans.

Other researchers have since concluded that there are

crucial differences in the genetic software of the two

species, however. Only a few months ago was the full

chimp DNA sequence unraveled.

 

Chimps evolving faster

In the new study, scientists examined how quickly each

species evolves. The figure they work with is called a

molecular clock. It involves the rate at which DNA

base pairs match up incorrectly, creating genetic

errors called substitutions. These are the mutations

that cause changes in a species over time.

 

Our clock began to slow down about 1 million years

ago, and today it is 3 percent slower than that of the

chimp and 11 percent slower than in the gorilla,

concludes the study, led by Soojin Yi, a biologist at

the Georgia Institute of Technology.

 

The upshot: There seem to be fewer changes to the

software of life in humans over time than in

chimpanzees, and even fewer still than in the other

apes.

 

This slower clock correlates with a longer time needed

to reach sexual maturity — almost twice as long for

humans as gorillas. Scientists call this " generation

time. " In order for mutations to cause lasting change

in a species, they must pass on to the next

generation.

 

Since well before modern times, humans have taken

almost twice as long to reach sexual maturity as other

apes, Yi said.

 

" A long generation time is an important trait that

separates humans from their evolutionary relatives, "

said Navin Elango, a graduate student working with Yi.

" We used to think that apes shared one generation

time, but that's not true. There's a lot more

variation. "

 

" I think we can say that this study provides further

support for the hypothesis that humans and chimpanzees

should be in one genus, rather than two different

genus' because we not only share extremely similar

genomes, we share similar generation time, " Yi said.

 

Humans slow but smart

Given our evolutionary snail's pace, you might be

wondering why, in just a few million years, we got so

smart while chimps lagged.

 

" Even though mutations per se may arise in fewer

numbers in humans than in chimpanzees, those that

matter will quickly spread, " Yi told LiveScience.

" Mutations that are advantageous to the human, such as

intelligence, probably are under strong natural

selection, " meaning individuals either latch on to the

good stuff or perish.

 

However, Yi and her colleagues looked only at

mutations in non-functional regions of DNA, changes

that don't affect evolution. " If we looked at only

those mutations that are selected, it is possible we

may see different results, " she said.

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