Human Hearts Streamlined for Stamina by Neolithic Revolution
New research suggests human hearts significantly changed when we dropped hunting and began leading more consistent lives as farmers, and now they are longer, thinner, and more flexible-walled hearts than chimpanzees.
The research, published in the journal Proceedings of the National Academy of Sciences, was led by Dr. Aaron Baggish, director of the Massachusetts General Hospital Cardiovascular Performance Program. Analyzing the differences between our hearts, and those of apes, they found the human heart has evolved over thousands of years to better suit modern life.
The Good, The Bad, And The Ugly
Dr. Baggish and his team investigated, measured, and compared the functionality of hearts in 40 semi-wild chimpanzees and five gorillas with the hearts of over 160 people. Assembled in four test groups the heart structures of American football players, elite runners, and indigenous Mexican subsistence farmers were studied alongside those from people who rarely leave their armchairs.
- Evidence suggests agriculture evolved independently throughout the world
- Hard-Working Prehistoric Women Had Stronger Arms Than Modern Elite Athletes
- Adapt, Diversify, Find a Niche: Survival Tactics of Homo Sapiens That Brought World Domination
Comparison of the LV structure and the function of the heart in chimpanzees and two representative human groups: sedentary Americans and Tarahumara subsistence farmers. (PNAS)
The researchers found that human hearts appear to have evolved to be better at handling endurance type activity as opposed to short intense bouts and if a heart is “particularly good” at one function it’s “conversely poor” at the opposite. The new findings suggest that while the human heart was at one time designed for short bursts to assist the demands of hunting and gathering, it became steadily more efficient at sustaining endurance tasks over increasingly longer periods of time.
Agricultural Tsunami Changed Everything
Just like when humans were hunter-gatherers, chimpanzees today engage in short bursts of activity climbing trees and fighting over resources, and their hearts provide oxygen under high pressure, for limited time periods. As humans adapted their lifestyles and took up agriculture there was a new demand to be active for longer periods of time and no longer did we depend on explosive bursts of hyperactivity.
A study published in the National Academies of Science Engineering and Medicine, says that about 11,000 years ago people in the Middle East began saving seeds from plants with favorable growing traits, and through this process of “artificial selection” the natural traits of wild wheat evolved quickly. Seeds remained on the stalk of the plant when ripe allowing for the easier separation from their hulls and at this time, all over the world, wild plants became crops and wild animals were domesticated into the placid ‘milkers’ we rely on today.
The human heart evolved to the agriculture lifestyle. (Bluemoose~commonswiki / CC BY-SA 3.0)
But don’t for a second conclude that plants, animals, and the human heart were all that evolved with agriculture, for ‘new pressures’ causes evolutionary change at a cellular level throughout the entire body.
‘Press’ Is For Pressure
Dr. Baggish says hearts “remodel" in response to two main forces: pressure and volume, and as their function evolved to maintain more constant energy levels, over a long periods of time, it resulted in what the researchers call a “less ape-like" appearance.
Imagine pressing a tennis ball against a solid surface and holding that constant pressure for 11,000 years. When you eventually take your hand away the ball’s structure it will have changed into a new shape which is resultant from changes in applied pressure over a long period of time. Now, that tennis ball is not only a great metaphor for Dr. Baggish’s new findings about the human heart but it might also represent every single individual cell in your body.
Pressurized Into Change
A study published in Scientific American explains that the conventional wisdom held in the field of historical linguistics is that human vocal apparatus has remained fixed since the emergence of Homo sapiens some 200,000 years ago. However, new paleoanthropological evidence has upended these assumptions suggesting that “pressure” caused by what, and the way we ate, entirely altered jaw anatomy which has profound consequences on how we speak.
The University of Zurich researchers said that among hunter–gatherers of the Paleolithic period, adults’ teeth aligned to form a flat line, the upper ones resting directly on the bottom teeth, caused by chewing hard unprocessed grains or seeds. The agricultural spike in the post-Neolithic period saw an increase of soft foods such as porridge and cheese causing the upper teeth to begin protruding over and above the lower teeth.
Changes in human lifestyle also altered jaw anatomy. (Nicolas Perrault III / Public Domain)
Evolving Backwards Into Illness?
Dr. Baggish’s new paper also pointed out that “changing pressure” has caused humans to have longer, thinner, and more flexible-walled hearts, while modern chimps have smaller, thicker heart walls. The research points towards human’s increasingly sedentary lifestyles causing this evolutionary shift that might also have caused our hearts to disease easier.
This thought provoking claim, that we really are what we eat, is amplified in a report in the Independent discussing the 2003 work of scientists from Liverpool and other universities in Europe and America, which suggests the million years old human diet of water, lean organic meats and fish, fresh leaves, nuts and fruit, is just about “perfect for the human body”. Notice there is no cheese, milk, or any other dairy products on that list, and for that reason the fat count is low.
The human body needs a diet of water, lean organic meats and fish, fresh leaves, nuts and fruit. (Alexander Raths / Adobe Stock)
These scientists concluded that today's chronic health problems result from dietary changes, and that a modern diet may do “as much harm to man as putting diesel in a petrol engine”. Effectively, high fat foods deposit fatty oils into the blood which line the artery walls causing an increase of “pressure” on the heart. Bottom line is, as a society, if we keep eating the crap we do our hearts will develop air filters and will required to be flushed out annually.
Top image: The human heart have evolved to be longer and thinner. Source: unlimit3d / Adobe Stock.
By Ashley Cowie