THE VENGEANCE FORMULATION AND THE GENETIC LINE

In “The Vengeance Formulation,” Season 3, Episode 9, the friends talk about the propagation of genetic lines.

The Book of Blood

Putting the three-breasted hooker from Total Recall to one side, “The Vengeance Formulation” episode touches on the topic of human makeup, what’s inside people, and the question of genetic lines. What, deep down and not just on the surface, is the difference between Coopers and Koothrappalis, Wolowitzes, and Hofstadters?

Let’s imagine Sheldon, standing in front of a mirror: what’s his genetic makeup? As a “typical” human, Sheldon’s body is made up of trillions of cells, the basic building blocks of all life on the planet. Cells come in many different types, of course, with each type doing a different job. Inside almost every cell, however, is the nucleus, which contains over 99 percent of your genes. Cells have mitochondria too, which contain a few more genes. Altogether, Sheldon’s body has around 20,000 genes.

Sheldon’s and everyone else’s genes are a small part of a chemical we call DNA. If you strung out the DNA of just one cell from Sheldon’s body, it would stretch, end to end, to about two meters long. And if you strung out the DNA from every cell in his body, end to end, it would reach from here to the Moon and back, three thousand times over. It’s clearly a place where a lot of chemical information can be stored. And the chemical language in which DNA is written we call the genetic code. The number and order of the chemical codes decide, for example, whether you are a banana, a chimpanzee, a cow, or Halle Berry. Most genes are recipes for making particular proteins, and these recipes are passed down through generations to make up the great variety of humans on Earth, Sheldon included.

When our bodies make new cells, very few mistakes are made. Once in a while, however, glitches happen. These glitches are mutations, and we all have them. When they occur, they’re passed down to the next generation. Inherited mutations are known as markers and are passed on along with the rest of the recipe of life. These markers turn out to be very handy, as scholars can use them to tell the tale of the Earth in human blood and bone. The markers become a type of time machine and enable us to find out about our ancestors. The blood yields the genetic code, and the bones act as an archaeological check on the time machine data. (By the way, the glitches don’t happen that often. Imagine Raj is copying out the longest possible book on astrophysics. And imagine he’s copying it by hand. The book is so long, Raj is working through the night with copious amounts of coffee in hand. Even though he’s very careful, and paying lots of attention, especially to those complex algebraic equations, once in a while he makes a spelling mistake. Same thing occurs to our DNA as it’s passed down through the generations. It’s how those infrequent markers occur.)

So, gene markers can act as a type of time machine. Using those markers, geneticists can look back into human history by using human blood. For blood carries its own history, and all humans are carrying pretty unique chapters in their veins. And that chapter will read differently for a Cooper or a Koothrappali, a Wolowitz or a Hofstadter.

Genetics scholars have learned how to read the time machine data in our genes. And they’re collecting more and more blood samples from people all around the planet. It’s on this basis, mainly, that they’ve come to the conclusion that all people alive today are related by blood, in one big human family of planet Earth. At the moment, the prevailing theory is that, not that long ago, there were only about 2,000 humans, living in a single continent: Africa. A small group of early humans left on a long journey. Sheldon and Leonard, and Raj and Howard, are among their children. But the incredible journeys different peoples took to populate the Earth is one of the most fascinating stories in human history.

Out of Africa

Though there are competing theories about the place of human origin, the current consensus is that Africa is the birthplace of everyone alive. Geneticists say that a DNA marker can be traced back, through the blood of different peoples, to the where and when that this marker was first found: Africa. For many thousands of years, homo sapiens lived throughout the African continent. About 60,000 years ago, they had started their steady journey out of Africa. Based on the speed with which today’s hunter-gatherer groups move, an average of less than a mile a year, our ancestors must have made slow progress, moving to new habitats and becoming isolated from other groups. And so the trend in human diversity began.

It’s incredible to think that evidence in the genes shows that the human population around 70,000 years ago had crashed to around 2,000 individuals. We nearly went extinct! But, hanging on by our Stone Age fingernails and even though the ice age must have made hunting pretty hard work, a small group of humans finally ended up in Australia. These intrepid travelers, and their descendants, took a beach-combing route along the coast of southern Asia. By 45,000 years ago, humans were living in parts of Australia. It’s in the blood, and it’s also in the bones. Archaeological evidence supports the idea that Aboriginal Australians have been on the continent for that long. They made campfires, which can still be detected, and they made their mark in cave art.

So, Australia was route one out of Africa. The descendants of the second route would become Asians, Europeans, and Native Americans. In short, everyone else on the planet. Geneticists believe they’ve found a marker in the genes of Chinese; Russians; Native Americans; Europeans, such as Coopers, Wolowitzes; and Hofstadters; and most Indians, such as the Koothrappalis. Incredibly, all these peoples share a marker inherited from a single male human in the distant past. He was in the second band of travelers to strike out of Africa. And they took an alternative route: to the Middle East.

This second small group of humans set out on a trek through the Middle East and into southern Central Asia. From locations there, humans were able to later journey to destinations in Asia, Europe, and beyond. One band made a journey into India. This bunch did so well that their numbers swelled, almost drowning all traces of the earlier coastal migration to Australia. So, humans got to India and Australia before they got to Europe.

Coming to America

Next stop on our round-the-world-to-America journey is Europe. Humans are thought to have first arrived to Europe around 45,000 years ago. At the time, Europe was a cold and icy place, so to help survive, their skin grew paler as a way to absorb more light. Coastal peoples, to the south of Europe, stayed a little darker-skinned, as they got plenty of vitamin D from seafood and fish. The ice age cut off the Europeans from the rest of the world for thousands of years. During this isolation, Europeans are thoughts to have grown in average height and developed a distinctive nose shape.

Population geneticists, the scholars who study the genetic differences within and among peoples, have recently made some new discoveries. Some now think there may have been three waves of European journeys, not just the one. Wave one was the hunter-gatherer people of 45,000 years ago we mentioned above, out of Africa but late of the Middle East, and whose ultimate destination was Europe. Wave two may have been early farmers, who journeyed into Europe about only 9,000 years ago and mixed in with the Europeans already living there. And wave three came from Central Asia. These people were the original humans who tamed the horse, and they’ve contributed DNA to a wide range of modern humans, including Native Americans.

The last leg of the journey finally takes us to the Americas. This final journey started in Asia and ended up peopling North and South America, from the Inuit to the Incas. The general consensus is that the ancestors of the Americans crossed from Siberia into Alaska. As the ice age sea levels dropped, a new landmass, named Beringia, rose up from beneath the Bering Sea. This new land provided a path from the Russian east coast into Alaska. And once the ice began to thaw, human explorers trekked down from Alaska, down a corridor east of the Rocky Mountains. Ice gave way to rolling prairies. Before them was a New World, an empty continent, with lots of roaming buffalo and mammoths.

This was not the journey of later Americans such as the Coopers, Koothrappalis, Wolowitzes, and Hofstadters, of course. That came later, when the US experienced major waves of immigration during the Colonial Era, the first part of the nineteenth century, and from the 1880s to 1920. And yet it was the journey of the First Americans. A journey that had begun in Africa, divided in Asia, and finally reached the last corner of the Earth, the last continent. Another group of humans had found a new home. Some scholars believe that gene markers show the first group to get to Alaska may have been as small as ten or twenty humans, but within 1,000 years, there were humans living in both North and South America. And what a journey: they’d survived drought, famine, and an ice age to get there.

So, even an off-hand remark during “The Vengeance Formulation” on the question of human makeup can have surprising answers, for Coopers, Koothrappalis, Wolowitzes, and Hofstadters all ultimately began as a small group of tropical Africans. They faced up to the challenges of survival and went on a series of incredible earthly journeys. It took them only 35,000 years to make the journey from Africa all the way to the New World. They’re members of one big family, separated by only 2,000 generations.