What make us human version 1.2

What make us human version 1.2? Why?? This post is the additional information of the post "what make us human". That post distinguish us from chimpanzees significantly from only 1% of DNA difference. From 1% difference involve genes that involve in brain development, opposing thumb and  facilitates formation of words by the mouth, enabling modern human speech.


This post I would to share with you the information that make us differ from chimpanzees in scientific evidence. Adult humans share features associated with immature chimpanzees,
such as small jaws and flat faces. The retention of juvenile features, called neoteny, may
explain why humans are so different from chimps despite a mostly similar genome.



In animals, neoteny comes about because of delays in development, points out molecular biologist Philipp Khaitovich of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. For instance, humans sexually mature roughly five years after chimps do, and our teeth erupt later. “Changes in the timing of development are some of the most powerful mechanisms evolution can use to remodel organisms, with very few molecular events required,” he explains.

To look for genetic evidence that neoteny played a role in the evolution of Homo sapiens, Khaitovich and his colleagues compared the expression of 7,958 genes in the brains of 39 humans, 14 chimpanzees and nine rhesus monkeys. They collected samples from the dorsolateral prefrontal cortex—a region linked with memory that is relatively easy to identify in the primate brain. These tissues came from deceased individuals at several stages of life, from infancy to middle age, enabling the researchers to see how genetic activity changed over time in each species.

In both humans and chimps, about the same percentage of genes changed in activity over time. But roughly half these age-linked genes in humans differed from chimps in terms of when they were active during development. Analysis of the 299 genes whose timings had shifted in all three species revealed that almost 40 percent were expressed later in life in humans, with some genetic activity delayed well into adolescence.


Actually proving that neoteny helped to drive human evolution and brain size is difficult. Khaitovich suggests analyzing genetic activity in cases of faster-than normal development in people, “which past research already shows can lead to a reduction in cognitive abilities,” he says.

Other experts certainly think that neoteny’s role is reasonable. The ability of the brain to learn is apparently greatest before full maturity sets in, “and since neoteny means an extended childhood, you have this greater chance for the brain to develop,”says molecular phylogeneticist Morris Goodman of Wayne State University,who did not participate in this study. In other words, human evolution might have been advanced by the possibilities
brimming in youth.