Our direct ancestor, Homo sapiens emerged on the World scene in equatorial Africa around 200,000 years ago and it is believed that 100,000 years later malaria for reasons that are not knowable the malaria parasite chose humans as its host, about the same time our ancestors also began migrating out of Africa. The image left suggests early humans migrated about Africa beginning 200,000 years ago, left Africa in waves beginning about 100,000 years ago, managed to wonder into Europe and Asia 50,000 years ago, crossed the Bering Straits 25,000 years ago and populated the Americas through 14,000 years ago. When I was a kid I was taught in school humans crossed the Bering Straits by boat being that it was thought there was no other way to advance. It appears now the Bering Straits 30,000 years ago was probably iced over, or more likely, since ocean levels were lower – the polar ice caps had more of Earth’s water locked up – the lower sea levels made for an ideal land bridge between Asia and Alaska. In fact, some 10,000 years ago or so England and Ireland were connected by land as was England connected to France by land. As the ice caps melted as part of the normal end to the last Ice Age, and as the oceans rose, those land bridges disappeared beneath a sea of…well…sea.
And as early humans migrated out of Africa, malaria migrated, too, hitching a ride with its migrating host, provided that the wandering was within favorable equatorial environs that also favored the mosquito. The image right sort of shows in blue those regions of Earth favorable to the mosquito, an insect needed for malaria transmission, and therefore the worldwide distribution of malaria, a parasitic infection that has its roots in Africa. In this regard, the end result of human migration was a worldwide equatorial distribution of malaria. Those malaria that chose sapiens who roamed north, into Europe or Asia, rather than east or west around the globe, roamed beyond the mosquito’s equatorial perch, trekking their way out of the mosquito’s reach, out of playing host to malaria.
I would be remiss if I did not mention that one sad migration that brought malaria to the Americas was, in fact not a migration at all, but a dark chapter in human history, the trans-Atlantic African slave trade. Although some strains of malaria likely made it to the Americas during the dawn of pre-historic man wandering into the Americas 12,000 years ago, it is quite likely that other strains of malaria found their way into the Caribbean islands, into Central and South America not from human migration out of Africa, not by crossing the Bering Strait land-bridge 30,000 years ago, but instead a mere 400 years ago, riding inside the blood of slaves brought from the African Slave Coast aboard slaver ships. When African slaves sick with malaria disembarked in the Americas, the malaria parasite disembarked with them.
Darwinian evolution played a role in sapient creatures eventually becoming us; it also played an odd role in why Walter Noel had sickle cell disease and might have been resistant to malaria as well. To appreciate this, let us review a few classic examples of evolution.
That first hominid who thought to walk upright on his hind legs was probably laughed at as a jester. But learning to walk erect, becoming bipedal, provided for several advantages: foraging for low-lying fruits, freeing hands and arms to carry infants, tools, food and weapons, walking was faster and more efficient than being on all fours when roaming the savannah, and being erect allowed for hunters to run while throwing spears or weapons. Many images depicting apes-to-humans walking upright almost always end with the final human being a Caucasian white dude. Nothing could be further from the truth. Upright walking humans, that is us, were originally dark-skinned and only our northern brethren wanderers became light-skinned. Why you ask? Up north in Europe the days were shorter, the Sun shown less and in order to absorb more sunlight for the conversion of vitamin D to its active form, life favored lighter-skinned humans. Another classic Darwinian survival adaptation. That is why I like the image depicted above of ape-to-human walking upright, it doesn’t depict skin color.
As an aside, if you were to shave an ape or monkey, their skin is light, it is whitish. As apes evolved into early man, it became decidedly disadvantageous to be too hairy as our ancestors left the canopy of the trees to roam the hot African savannah. Those early humans who were less hairy were favored simply because they could withstand that hot, bright noon day Sun, yet another classic genetic adaptation. But it didn’t end there. Those less hairy humans had their pinkish white skin now exposed to the Sun’s harmful rays. So in a subsequent genetic adaptation, life favored those less-hairy, darker-skin humans. When Homo sapient reached its current final form in Africa some 100,000 years ago or so, he and she were much less hairy dark-skinned wanderers. It was only those ancestors who ventured into Europe that became light-skinned, yet another genetic adaptation.
Our opposable thumbs were also key to separating us from our primate ancestors; primates have flat hands with the thumb on the same plane as the other fingers. Over time, the sapient thumb started to rotate on its axis, initially as a genetic aberration but this rotation allowed the thumb to “oppose” the other four fingers; by having such an “opposable thumb” it provided for our ancestors to use tools, develop a power grip and perform precision work.
Using tools was and is one thing that is for the most part, uniquely human. I imagine the first hominid whose thumb was slightly rotated was made fun of; that is until she picked up a club and whacked her tormentor over his hairy head.
Another uniquely human trait is being able to “kill” from a distance. When you’re foraging for food and you’re tired of eating berries – you really want to “get your beef on” – using that spear you fashioned, a tool, and being able to take down an animal without actually having to wrestle with it, that is, being able to throw a spear from a safe distance, well, that is a uniquely human advantage, too. The first sapient who took a stick and whittled one end into a point was likely thought to be deranged, that is, until he threw that pointy stick into a wild boar. Then he was celebrated, still thought of as deranged, a tad scary, but celebrated because he was able to kill from a distance.
For you Alien versus Predator aficionados out there and who’d win such a fight, well I’ll open that can-of-worms. In close quarters most likely the Alien would win because the Predator wouldn’t be able to arm itself fast enough, all things being equal. But in open combat, Predator can kill from a distance making it the superior warrior to Alien, regardless of the beautiful Sigourney Weaver’s Ripley and her thoughts on the matter.
Whatever the genetic evolutionary aberration, if it provided a desirable mutation or adaptation that granted a favorable heritable trait, it was passed on, generation-by-generation, slowly, most assuredly. Remember that when we circle back to the connection between malaria and sickle cell anemia.
…stay tuned for future posts…
John Bershof, MD
John Bershof, MD is a plastic surgeon who has been in private practice for over 25 years. He is the author of numerous medical articles as well as the first textbook of medicine for mobile phones, entitled skynetMD 2005-2015. An essay entitled Gin & Tonics, Clerics, and Dr. Livingstone, I Presume?, which was extracted from one of his future as yet published books was featured in The Antioch Review.
While working on the medical textbook skynetMD for mobile phones, Dr. Bershof, perhaps not too surprisingly became more interested in the backstories of medical history, like who was Lou Gehrig, what is Lou Gehrig's disease, what was his lifetime batting average for the New York Yankees—.340, nineteenth overall—and who invented baseball anyway. Questions such as these piqued Bershof's interest. Having read At Home 2010 by Bill Bryson, his engrossing narrative journeys room-by-room through his Victorian English countryside home, a former rectory, where each room is a chapter about domesticity, about home. It occurred to Dr. Bershof that in similar vein he could take the reader disease-by-disease as jumping off points into human history, science, medicine—his canvas blank, no subject not within reach—and learn a little medicine along the journey.
The ability of a book that is heavily fortified with science and history to connect with a general readership can be challenging; Dr. Bershof through storytelling, humor, jumping off points and personal anecdotes, accomplishes it, written in a language fleeced of the jargon that normally accompanies such narratives. The first two books, The First History of Man published in 2020 and The Second History of Man published in 2021 are available in print, ebook and audio. The Third History of Man is in final stages of editing to be published in 2022, with more volumes to come after that.