The Primates: Humans - 4 views
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all lack external tail
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thumb that is sufficiently separate from the other fingers to allow them to be opposable for precision grips.
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sexually dimorphic--males are 5-10%
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we are omnivorous.
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same arrangement of internal organs and bones
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many of the same diseases
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share several important blood types
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Unlike apes, our arms are relatively short and weak compared to our legs
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modern human brain is 3 times larger in volume
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toes became shorter and the big toe moved up into line with the others.
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The pelvis
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Nature very likely selected for longer legs
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downside of the evolutio
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we are quite similar to the African apes anatomically and genetically, especially to the chimpanzees and bonobos
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minor anatomical differences between humans and apes
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46 chromosomes
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longer legs require less up-and-down movement while running and, therefore, reduce the amount of energy needed to move rapidly
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allow humans to travel farther with the same calorie expenditure
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changes in the pelvis which unfortunately included a narrower birth canal in females.
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A partial evolutionary solution to this birth difficulty for humans was fetuses being born at a less mature stage, when their bodies are smaller. The trade off is that human newborn babies are more vulnerable.
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This vulnerability translates itself into an immature brain. In the baby's first year, the brain grows dramatically. In fact, humans have more synapses (connections between neurons) at this young age than in any other time of life.
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Evolving a larger brain comes at a steep energy cost. The human brain uses about 25% of the energy derived from the nutrients that we consume and 20% of the oxygen.
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HAR1F regulator gene beginning about 6 million years ago
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7th and 19th week after conception
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People have much more complex forms of verbal communication than any other primate species. We are the only animal to create and use symbols as a means of communication.
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We also have more varied and complex social organizations. The most distinctive feature of humans is our mental ability to create new ideas and complex technologies.
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mental levels equivalent to a 3-4 year old human child
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they do not have the capability of producing human speech and language
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Female chimpanzees, gorillas, and other non-human primates usually remain capable of conception and giving birth even when they are very old