Category Archives: Evolution

Sedentary lifestyle NOT an option here

I had lots of evolution indoctrination during study for my zoology degree. It helps me understand the following.

From BioEssays:

Most people are aware of the health benefits of being physically active. The question arises then why people so easily fall into sedentary habits. The idea developed here is that sedentary behavior is part of a suite of behaviors to reduce levels of physical activity that were strongly selected in the evolutionary past, likely because high levels of physical activity had direct negative consequences for survival. However, hunter-gatherer populations could not reduce activity indefinitely because of the need to be active to hunt for, and gather food. Hence they never experienced low levels of activity that are damaging to health, and no corresponding mechanism avoiding low activity evolved. Consequently, gene variants promoting efficiency of activity and increased sedentariness were never selected against. Modern society facilitates reduced activity by providing many options to become less active and divorcing food intake from the need to be active. Choosing the less active option is hard wired in the genes; this explains why being sedentary is so common, and why reversing it is so difficult.

Source: An Evolutionary Perspective on Sedentary Behavior. – PubMed – NCBI

Steve Parker, M.D.

Click pic to purchase book at Amazon.com. E-book versions available at Smashwords.com.

Fresh off the Bering Strait from Siberia?

From Ancient Origins:

“Archaeologists have found a set of butchered bones dating back 24,000 years in Bluefish Caves, Yukon, Canada, which are the oldest signs of human habitation ever discovered in North America. Until recently, it was believed that the culture that represented the continent’s first inhabitants was the Clovis culture. However, the discovery of the butchered bones challenges that theory, providing evidence that human occupation preceded the arrival of the Clovis people by as much as 10,000 years.

For decades, it has been believed that the first Americans crossed the Bering Strait from Siberia about 14,000 years ago and quickly colonized North America.”

Source: 24,000-Year-Old Butchered Bones Found in Canada Change Known History of North America | Ancient Origins

An article at ArsTechnica makes the argument:

“The standard story of how humans arrived in the Americas is that they marched 1,500km across the Bering Land Bridge, a now-vanished landmass between Siberia and Northern Canada that emerged roughly 15,000 years ago in the wake of the last ice age. But for the past decade, evidence has been piling up that humans arrived in the Americas by traveling in boats along the Pacific coast. Some 14,000-year-old campsites like Oregon’s Paisley Caves have been found near rivers that meet the Pacific, suggesting that early humans came inland from the coast along these waterways. Now, a new study published in Nature provides more solid evidence the first humans to reach the Americas could not have come via the Bering Land Bridge.”

Source: Time to scrap the idea that humans arrived in the Americas by land bridge | Ars Technica

Richard Wrangham figures our hominin ancestors tamed fire and started cooking with it 1.8 million years ago. Other authorities date our mastery of fire from 12,000 to 400,000 years ago.

From the New York Times:

“When early humans discovered how to build fires, life became much easier in many regards. They huddled around fire for warmth, light and protection. They used it to cook, which afforded them more calories than eating raw foods that were hard to chew and digest. They could socialize into the night, which possibly gave rise to storytelling and other cultural traditions.

But there were downsides, too. Occasionally, the smoke burned their eyes and seared their lungs. Their food was likely coated with char, which might have increased their risk for certain cancers. With everyone congregated in one place, diseases could have been transmitted more easily.”

Source: Smoke, Fire and Human Evolution – The New York Times

Writing at TheScientist:

“Skin color is a classic example. One of the largest and most obvious physiological differences between populations, skin color is influenced by more than two dozen genes in a pathway that produces the pigment melanin and regulates the amount of this pigment in different tissues. Changes to these genes interrupt the generation of the dark pigment eumelanin, leaving skin with larger amounts of the reddish pigment pheomelanin, leading to various skin tones and patterns of coloration, such as freckles. Despite its complex genetics, skin color shows consistent patterns of evolution across the globe. People whose ancestors lived in the tropics tend to be dark-skinned, while those who lived further north and south tend to be lighter. One of the revelations of the last 15 years is just how recent this pattern really is. According to analyses of ancient DNA, people who lived in northern Europe only 10,000 years ago would not have had the extremely light skin of today’s people in that region.”

Source: Humans Never Stopped Evolving | The Scientist Magazine®

Hawks also discusses lactase persistence, eye color, blood types, and malaria resistance.

“Archaeologists in Texas have found a set of 16,700-year-old tools which are among the oldest discovered in the West. Until now, it was believed that the culture that represented the continent’s first inhabitants was the Clovis culture. However, the discovery of the ancient tools now challenges that theory, providing evidence that human occupation precedes the arrival of the Clovis people by thousands of years.”

Source: 16,700-Year-Old Tools Found in Texas Change Known History of North America | Ancient Origins

When I first read this, I thought it outdated my Paleobetic Diet book. But no. On page 33 I wrote, “Northeast Asians moved into North America (Alaska) 12 to 30,000 years ago.”