Chapter 16 Legacies ofHuman Evolutionary History

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

Our biology is the result of millions of years of evolutionary history:– 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

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

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

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

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

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

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

Infectious diseases - Several have become resistant to antibiotics.

Insects - Use of insecticides has resulted in many becoming resistant.