Humans – Us vs. them?

Nope, not so much. Them pretty much are, us. Or to say it another way, we.

None of us picked the circumstances of our birth or who our parents were. None of us picked where we were born. None of us choose the economic circumstance we were born into. At birth, many of the things about our health, looks, orientations, and other traits are given us. We can’t take credit nor do we deserve blame.

So we can’t be blamed for being born who we are. but the question is biologically / genetically just how different are individual people from other individual people?

Biologically this is pretty easy to show. Adult Humans of child bearing age from anywhere on earth can mate with other humans of child bearing age from anywhere on earth and produce fertile offspring. If our DNA were substantially different that would not be possible. All humans are the same species: Homo sapiens. By definition that means they can successfully mate with each other.

In fact, on average, 99.5% (more if you are a biological relative) of our DNA sequence is the same as any other individual human on the planet. In plain language, we all have skin, bones, organs and the like. We have brains and toes and eyes and a mouth and the list goes on. Genetically speaking, for about 99.5% of our DNA; just by looking at the DNA, you can’t tell one of us from another.

But we have all noticed that some of us are taller than others. Some of us have different pigment color in our eyes. Some of our skin tones are lighter than others. Some are more susceptible to a certain disease than another person. These kinds of traits are controlled by the “0.5% of the DNA”. The traits we have from mom and dad creating a new person are 99.5% the same as everyone else but 0.5% are the result in the dominate and recessive gene combinations. Think of it this way, if the combinations of DNA in “the 0.5%” was not survivable, sadly, nature takes its course. Since we survived, we are essentially the same as any other human who survived.

All of our ancestors originated from central Africa about 200,000 years ago. We migrated from Africa to Europe and Asia (125,000 to 60,000 years ago) and Australia about 40,000 years ago. Then to the Americas about 15,000 years ago. Finally, to remote islands (Hawaii, Easer Island, Madagascar and New Zealand between 1,300 to 300 years ago.

Hey wait a minute! Have you seen the test your DNA commercials? We must be different from each other because they can tell who our ancestors are including what different regions our ancestors lived. Plus, people from different regions often look different from people in other regions.

No two humans are considered to be genetically identical. Human genetic variation results from the mixing of the genes of mom and dad and once in a while a mutation. But that said, all humans are very much genetically the same. So how can those DNA sample analyses stand up in court. How can those ancestry companies tell where your ancestors lived?

The current state of genetics looking at these differences one can determine a couple things:

  • If individuals are closely related (Is the deceased, your long lost multi-millionaire brother?)
  • Chromosomal crossover from combining mom and dad. Think recessive and dominate genes causing things like eye color, pigmentation of skin, height and other traits which can be seen and other traits such as pre-disposition to a disease, or pain tolerance, etc. which are not as readily seen.
    • Geographical and ancestral trending. Did the sample have characteristics matching ancestral populations known to have been in one continent or another (genetic distance) partially match this sample.

Note: Travel between the continents (ships and planes) over the past 300+ years have mixed the gene pool. Most people on earth have genetic indicators for multiple geographical and ancestral areas. When you see those ads for ancestral testing and the actor exclaims how surprised they were to discover their ancestors came different areas of the world, don’t be that surprised. Almost everyone on earth has ancestors that came from somewhere else. Most of us had ancestors from multiple other places.

So let me summarize.

All humans alive on earth are the same species from the same place 200,000 years ago. Over thousands of years, our ancestors migrated from continent to continent. Some minor differences between the genetic makeup of individuals from one continent to another emerged. But travel between continents over the past couple hundreds of years have mixed the DNA and made even these minor differences in the genes between individuals even less significant.

Here are a couple related points I feel should be made.

Skin pigmentation is determined by the genes of one’s biological parents. Until about 30,000 years ago all humans are thought to have dark skin. Then mutations of two genes caused lighter skin. Because some of these light skinned people were in climates with less ultraviolet radiation, northern Europe and east Asia, they were able to survive even with this light skin. As many people with light skin have discovered, exposure to excessive ultra violet radiation can lead to serious health consequences. From a genetic point of view, skin color is the result of small number of DNA pairs passed on by your parents and not an indicator of much else.

In a related note one of the benefits of the chromosomal crossover from different areas of the earth can improve our resistance to environmental factors such as the sun, cold, altitude, etc. Same is true for some diseases. It would be much easier for a single pathogen to wipe out an entire population if everyone had the exact same gene set. Our minor differences actually can help all of us.

So the final conclusion

At a genetic level, trying to distinguish between us and them is a fool’s errand. Pretending there is significant difference between populations of us and populations of them, is wrong factually and not good for the survival of the human species. I happen to believe it is also morally wrong but that is another story and we need to define morality before we get there.



I am listing the data below just to show some perspective (the name of this blog is Scale and Perspective after all) on how many humans there are and their current geographic distribution.

  • Human population on earth = 7.4 billion.
  • # humans have ever lived = about 108 billion. So about 6% of the humans who have ever lived are alive now.

Distribution of humans by continent

  • Asia = 4.4billion = 59.6% of total
  • Africa = 1.2 billion = 16.3%
  • Europe = 738 million = 10%
  • North and Central America = 579 million = 7.8%
  • South America = 422 million = 5.7%
  • Oceania = 39.9 million = 0.5% (Australia, and the islands of the tropical Pacific Ocean)
  • Antarctica = 1,200 non-permanent = 0.00002%