Transcript Biocultural Evolution

Chapter 16 Legacies of
Human Evolutionary History
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Biocultural Evolution and the Individual
Evolution and Society: Behavioral Ecology
Human Impact on the Planet and other Life
Forms
Are We Still Evolving?
Biocultural Evolution
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Our biology is the result of millions of years of
evolutionary history:
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225 million years of mammalian evolution
65 million years of primate evolution
6 million years of hominid evolution
2 million years of evolution of the genus Homo
Biocultural Evolution and the
Individual
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Intelligence, body shape and growth result from
interaction of environment and genetics
Good health and adequate nutrition are important for
children to reach their genetic potential for height.
Socioeconomic status is one cultural factor that affects
growth.
Brain Growth
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Pattern of human brain growth:
– At birth the brain is about 25 % of its adult size.
– Six months after birth it has doubled in size and
reached 50% of its adult size.
– By age 5, the brain has reached 90 % of its adult
size.
– By age 10 the brain is at 95 % of its adult size.
Nutritional Adaptations
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Shaped in an environment that included times of
scarcity alternating with times of abundance.
Amino Acids required in human nutrition reflects an
ancestral diet high in animal protein.
Preagricultural diet - high in animal protein, low in
fats.
Ability to store fat was an advantage in the past.
Human Longevity
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The maximum life span of 120 years has not
changed in the last several thousand years.
One explanation for degenerative diseases:
genes that enhance reproductive success may
have detrimental effects in later years.
Overpopulation
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Human population increases worldwide at an
annual rate of about 1.8%.
We add 90-95 million people to the world every
year.
If not curbed, human population will reach 10
billion by 2050.
Extinction
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In the past 570 million years, there have been
at least 15 mass extinctions.
1. 250 m.y.a. - result of climatic changes and
the creation of one supercontinent.
2. 65 m.y.a. - ended 150 million years of
evolutionary processes that produced
dinosaurs.
3. Current - recent and ongoing extinctions
are due to the activities of Homo sapiens.
Acceleration of Evolutionary
Processes
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Infectious diseases - Several have become
resistant to antibiotics.
Insects - Use of insecticides has resulted in
many becoming resistant.