science 29 january 2010 (327) p532.. humans are a product of natural selection … … and are...

Science 29 January 2010 (327) p532.

Humans are a product of natural selection …

… and are adapted to their environment.

Milk contains milk sugar or lactose. Digestion of lactose in the small intestine requires

galactosidase or lactase.

Lactose intolerance: results when the small intestince no longer produces lactase.

Percentage of people lactose intolerant.

Global map showing the frequency of the lactase persistence trait for populations reported in

Ingram et al.

Scheinfeldt L B et al. PNAS 2010;107:8931-8938

©2010 by National Academy of Sciences

Linearbandkeramik (Funnel Beaker) pottery cultureOrigin of Lactase Persistence7500 – 3500 years ago

the limits of the geographic distribution of early Neolithic cattle pastoralist (Funnel Beaker Culture)

Dinka and cattle (southern Sudan)

Dinka cattle camp (southern Sudan)

Massaai and cattle (Tanzania, Kenya)

Mountain climbers suffer from high-altitude illness and shortage of oxygen.

Living in Denver, CO: the mile-high city.

Tibetan Plateau: ~4000 m and inhabited for ~ 25,000 years.

PHD

VHL HO-

+

HRE

CBP/p300

ErythropoetinVGEF

Poly-ubiquitination

Proteasomaldegradation

Normoxia

Hypoxia

Ubiquitin

Nucleus

That the HIF-mediated increase in hemoglobin concentration is a misdirected response to hypobaric hypoxia that originally evolved as a response to anemia.

In anemia, reduced tissue oxygenation is caused by a curtailed oxygen transport capacity of the blood, and can therefore be rectified by increasing hemoglobin concentration.

By contrast, in hypobaric hypoxia, the reduced tissue oxygenation has an external cause: The reduced oxygen tension of inspired air leads to a reduced oxygen saturation of arterial blood. Under these circumstances, a dramatically increased hemoglobin concentration may further impede oxygen delivery to metabolizing tissues.

Science 2 July 2010, 329 p40.

The ability to tan is driven by evolution …

To tan is a trait that evolved several times in mid-latitude regions,where the sun’s intensity varies dramatically from season to season

Sunbathers who bronze beautifully have natural selection to thank.

Absorb UV light and make Vit D in winter, protect Folic Acid from light in summer

Among women who inhabit the Bolivian Altiplano, which rises some 12,000 feet (7,300 m) above sea level, the uterine artery undergoes accelerated growth during pregnancy compared with the growth seen in women from low-lying regions – an adaptation that has evolved within the past 10,000 years.