Humans Have Evolved to Reproduce, Not to be Healthy

Wednesday, February 05, 2014

Daniel E. Lieberman, chair of the department of human evolutionary biology at Harvard University, tells us how the human body evolved over millions of years, and explains how we’ve ended up living longer but with more chronic disease. The Story of the Human Body: Evolution, Health, and Disease shows how cultural evolution differs from biological evolution, and looks at the modern conditions to which our bodies are not well adapted, resulting in more obesity and diseases such as type 2 diabetes.

Some Interview Highlights

Are our bodies adapted to be a hunter-gatherer on the Serengeti? The answer is complicated.

We're still evolving, Daniel Lieberman pointed out, and that cultural evolution is as important in shaping humans as biological evolution. When our ancestors invented special clothing (like heavy wool), it enabled us live in different environments, which has led to natural selection to operating in important ways. "Cultural and biological evolution are not independent. In fact they're deeply woven together," said Lieberman.

We are hardwired to crave foods with salt, sugar, and fat. For example: babies take a long time before they're independent enough to feed themselves, and mothers need a lot of energy to be pregnant, breastfeed, and to take care of children. Humans needed a lot of fat and calories to fuel active lives and to get through times when there wasn't enough food.

Lieberman said there are good and bad things about the Paleo Diet. There's no question that the healthiest diets are low carb, low sugar because we're poorly adapted to handle simple carbs and sugars. But he thinks the Paleo Diet's restricting dairy and legumes is going too far. "It makes the assumption that if we've evolved to eat it, it must be healthy," Lieberman said. "But we evolved to reproduce, not to be healthy."

Processed foods change the way our digestive system functions. When food is ground, cooked, etc., our digestive systems can break it down faster. One of the problems with our digestive system is that it has never evolved to adapt to the amount of sugar we eat today. 

Cavities are a modern affliction. The modern human diet, which includes more cereals and sugars and starches, has led to tooth decay because the bacteria that live in our mouths love simple starches and sugar. The bacteria feed on them, produce acid, and that acid causes cavities.

How did allergies evolve? Lieberman explained that we used to be bombarded with germs and bugs and worms and dirt. Now we've removed a lot of the demands our immune system with cleanliness, and the leftover immune responses are attack the wrong things and are attacking our own bodies. 

We're living longer but we're sicker. We spend too much time treating symptoms of diseases rather than causes. Looking at evolution can help us identify the causes of these diseases and know how to prevent them.


Daniel Lieberman

Comments [28]

PJ From NJ from New Jersey


I know this probably violates message board etiquette, but you are the worst form of person!

There was a time when you did not know the things you know and others shared their knowledge with you. So if you have knowledge you would like to share, then share it. There is no reason to be angry or attempt to diminish Leonard's intellect. He wasn't stating opinion but was asking questions based on his observations (whether correct or incorrect).

Grow up!

Feb. 23 2014 02:27 PM

I can't believe that the "hair" issue was not connected, and it wasn't brought up at all, to sexual selection. The hair evolution issue has to do much more with sexual selection!! Skin is sensitive and sensual! Heeelloo! not just cooling.
Nordics are not less hairy!?! blond hair is less visible,and blond beard; I suppose you haven't seen a Swedish woman's legs in winter.... they're very hairy! Scandinavian man have thick beards! in what planet have you been? And the hairiest people are red haired people, no ill intended, I love red haired people! I love Swedish too, but they'll confirm they're hairy! Vikings! (the stereotype, hairy!) Germans? Irish? do you really think they're less hairy! Honestly Lopate, sometimes... one wonders!
We didn't start losing hair after we become bipedal, orangutans, gorillas and chimps, our closest relatives don't have hair on their feet and they're not bipedal! Unbelievable!!
Peanut is a completely genetically modified thing, that didn't exist in nature, it's a laboratory invention, that's why the Paleo diet is against it, because it's against any GMOs, and most legumes like soy, peanut, and peas are a form of earlier GMO.
I apply a modified Paleo diet in my home, with pro-biotic yogurt, some cheese, milk in general should be avoided when we're adults.

Feb. 06 2014 10:19 AM
Steve from Catskills

jgarbuz - i'd like to know how it is you consider cheese not to be dairy.

Feb. 05 2014 11:44 PM
Truth & Beauty from Brooklyn

Amy from Manhattan: Your dentist may be correct; however, it is my observation that humans are developing larger mouths so they can fit in as many feet as necessary...

Feb. 05 2014 01:26 PM
emjayay from Brooklyn

Matt: Losing the ability to digest lactose as adults is normal for all mammals since they don't need that ability. A certain percentage of humans can anyway. Certain populations like Northern Europeans evolved more in that direction in the past thousands of years. See my other comment for the story (well my version), which is easily accessible from many sources.

Feb. 05 2014 01:12 PM
emjayay from Brooklyn

The Truth from Becky: Re lactose - if you had been paying attention you would have heard the guest explain, at least basically. In certain parts of the world like Europe with the start of agriculture humans started getting milk from animals. No other mammals get milk from other species. It got some people who could digest it later than most humans through some tough times. More of those people who retained the genes for adult lactose digestion survived and were able to reproduce survived than those who didn't. That's how evolution works.

In many areas of the world there weren't animals you could milk. So there are a lot fewer Asians and Native Americans (who are basically Asian) and Africans who can digest lactose as adults. Northern Europeans are around 90% able to digest lactose as adults, and Asian populations are exactly the opposite. Hence, a lot of soy milk at supermarkets in more Asian neighborhoods. Overall, about 25% of humans can digest lactose as adults. I think there are also people who are in between.

Anyway, this information is easily accessible from multiple sources.

Feb. 05 2014 01:06 PM
Sarah, sustaining member from CT

Again I will ask - Please, please can you differentiate between Type 1 and Type 2 diabetes? It's such a painful thing for my Type 1 teen (diagnosed at 4 years old) and budding scientist to have to listen to an interview with someone she finds fascinating only to hear both Mr Lopate and Dr Lieberman go on about "diabetes" and diet. You should both know better and you wouldn't do that if your kid lived with Type 1.

Feb. 05 2014 12:48 PM
Amy from Manhattan

Whatever ability humans have to adapt to the effects of global climate upset won't help us if great numbers of other species (both plant & animal) that we depend on die off.

Feb. 05 2014 12:44 PM
The Truth from Becky

What about dairy? Why is it so hard for some to digest lactose?

Feb. 05 2014 12:41 PM
The Truth from Becky

Is that really a good thing? You are just both wrong.

Feb. 05 2014 12:40 PM
jgarbuz from Queens

to illfg

Cain and Abel may be a simplified tribal story referring to Neanderthals (who were numerous in ancient Levant and story of the Cro-Magnon who eventually superceded them. Jews don't take the Bible too literally as do Evangelical Christians, but neither do we totally dismiss it as just myths and fairy tales.

Feb. 05 2014 12:39 PM
Amy from Manhattan

My dentist years ago told me that people were evolving toward having smaller mouths w/room for fewer teeth, & that was why people get impacted wisdom teeth. This can't be true for all groups of humans--maybe certain societies create evolutionary pressure that leads to this development? Does this make any sense to Dr. Lieberman? If so, what does he think explains it?

Feb. 05 2014 12:39 PM
John A.

Equally interesting might be how culture evolves in and out of being beneficial to the individual. From being supportive and giving to being competitive and taking. This includes corporations being celebrated for maximizing profits by taking advantage of individuals. Society should *not* support such things, but we're into it now.

Feb. 05 2014 12:38 PM

YAY me and jgarbuz agree on something!

Feb. 05 2014 12:37 PM
jgarbuz from Queens

to illfg

We agree on Atkins, and disagree on God. As for "religion," those are just taboos some of which make sense, and others do not.

Feb. 05 2014 12:36 PM
jgarbuz from Queens

I've been on the Dr. Atkins "paleo-diet" since 1997 and it has worked well for me. No sugar. No dairy. No bread and cookies nor candies and the like, and plenty of protein and cheese. Low carb veggies and berries too. Dr. Atkins is my eternal doctor and the only one I've needed so far at age 67.

Feb. 05 2014 12:35 PM

@jgarbuz from Queens
The answer is neither. Cain and Abel are fairy tales. Religion is fantasy used to control people. being religious is a mental illness.

Feb. 05 2014 12:34 PM

Dr. Atkins is vindicated yet again.

Feb. 05 2014 12:32 PM

Why do we develop allergies and intolerances as we get older? Like developing a lactose intolerance as an adult, for example.

Feb. 05 2014 12:31 PM
Mark from Bronx

We commonly see what appear to be "not so modern" indigenous people on various "National Geographic" type programs. Are these people on the same evolutionary scale. What problems or advantages would this type of person encounter in modern NYC?

Feb. 05 2014 12:28 PM
Todd from East Village

Mr. Lopate, sciatica and back pain are mismatch diseases as well. See the work of Esther Gokhale, who argues we've lost our postural tradition. We sit stand and walk very differently from pre-industrialized people. Hunter gatherers and other pre-industrial societies do not have the muscular skeletal issues of western societies.

Feb. 05 2014 12:27 PM
jgarbuz from Queens

Cro-magnon and Neanderthal. Cain and Abel? Are we the children of Cain?

Feb. 05 2014 12:25 PM
jgarbuz from Queens

Cro-magnon and Neanderthal. Cain and Abel? Are we the children of Cain?

Feb. 05 2014 12:24 PM
Judy from Oakdale

The new study, in the August 2013 print issue of the Journal of Investigative Medicine, found a 65 percent increase in IBD hospital discharges from 2000 to 2009. The number increased from 11,928 discharges in 2000 to 19,568 discharges in 2009.

IBD refers to a group of inflammatory conditions of the colon and small intestine. The major types of IBD are Crohn's disease (CD) and ulcerative colitis (UC). When looking at these two types of IBD individually, the authors found a 59 percent increase in CD discharges and a 71 percent increase UC discharges.

The study looked at more than 11 million hospitalization records of patients 20 years old and younger using a federal children's inpatient database. For the decade, they identified more than 61,000 pediatric discharges with an IBD

Feb. 05 2014 12:24 PM
Judy from Oakdale

What about GMO foods and health: Science Daily released a report in Aug 2013 that stated Inflammable Intestinal Disease IBD has increased by 71% since 2000 the same occurrence is seen in pigs fed GMO animal feed?d

Feb. 05 2014 12:20 PM
Kellyn from Midtown

What about people who are hairy all over; their backs, legs, ears, foreheads, arms.. surly that's fur!?

Feb. 05 2014 12:17 PM
Bonn from East Village

Apparently you have never met my niece's husband, who is a total fur ball all over his body. His young son is the same. They have to shave his chest, back, arms or he will be ridiculed. What evolutionary process happened to them?

Feb. 05 2014 12:16 PM
Ed from Larchmont

Evolution is part of the instrumental cause as to how our bodies became what they are, but the final cause is what God wished to create when he made man. Evolution was just the elegant way to do it. (In the O.T. one sees the care and exactness that God asked the Jewish people to use in making the Temple, for a Christian the temple is the human body, and even more exactitude and precision went into fashioning it.) If we aren't able to deal with our environment, it might be that we've altered our environment too much.

Feb. 05 2014 12:03 PM

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