Celebrating the human condition
The message came through loud and clear.
Dr. Michael Hammer of the University of Arizona was matter-of-fact in what he said.
He didn’t shout.
He didn’t even raise his voice.
But the message sang out in the conference room at the 13th International Genetic Genealogy conference in Houston yesterday.
Only a tiny fragment of the differences between human beings comes from actual diversity. We are, Dr. Hammer said, so much more alike than we are different… and decades of research into the human genome has disproved the concept of race as a divider among people.
In fact, there’s a lot more diversity among groups of chimpanzees — or just about any other kind of mammal you can think of — than there is between groups of humans.
“The story of human diversity is an outlier,” Dr. Hammer declared. “The changes from one person to another are tiny compared to the genomic evidence that we are alike.”
Now if anybody ought to understand a little about the forces of genomics in human history, it’s Michael Hammer. With a Ph.D. in genetics from the University of California at Berkeley followed by research at Princeton and Harvard, he’s a research scientist who’s worked in the laboratory on human evolutionary genetics for the past 25 years and now serves as Director of the University of Arizona Genetics Core (UAGC).
And, yesterday, at the annual Family Tree DNA project administrators’ conference, he gave the attendees a rundown on the top 10 genomic developments that research has uncovered. His top 10 list, from 10 down to 1, was:
10. More than 98% of the human genome is shared with our closest relatives, the chimpanzees.
9. Humans are less genetically variable than any of the other great apes.
8. There’s little difference between human groups, and no subspecies in modern man.
7. The Human Genome Project has disproved the concept of race.
6. Diversity among humans is clinal, meaning what differences we do see are those that have developed gradually among related peoples from causes like climate.
5. The small number of genetic differences that do differentiate us generally result from natural selection, with a very small number of genetic markers responsible for differences like skin color. A single genetic marker, called a SNP, is responsible for 30% of the difference in human skin coloration.
4. There are more differences genomically among populations within Africa than between continental populations.
3. Interbreeding with Neanderthal and similar populations may have been more common in human evolution than we thought. One skeleton from roughly 40,000 years ago was shown to have 6-9% Neanderthal DNA.
2. Explosive population growth in the modern era has brought a correspondingly explosive growth in rare and even harmful genetic changes. About 75% of genetic markers arose in the last 5000 years and about 15% are harmful.
And the top development:
1. Fathers pass down more mutations — changed genetic markers — to their children than mothers do, and older fathers are responsible for more mutations than younger fathers.
Put it all together and there’s one fundamental message of those developments: every human genome is a mosaic of everyone who’s gone before us — and every human genome today is so very much like every other human genome.
More powerful than concepts of race that people use to set us apart. More compelling than physical attributes that people use as differentiators.
The scientific evidence is clear.
What’s in our genes is proof positive that we’re all very much the same at the genomic level.
What’s not in our genes is any difference that makes any difference at all.