Learning From the 400,000 Year Old Man (12/18/13)

Where We All Come From

Is North Korean dictator Kim Jong Un scared of a thighbone? One that’s 400,000 years old?

He should be.

A bedrock of North Korean ideology since the 1940’s has been North Korean’s racial homogeneity and superiority over everyone else – particularly hybrid Americans.  It’s one way you can keep a starved population both cowed and proud.  We’re better than everybody else – smarter, braver, shrewder, stronger –and purer.

But like most of the regime’s story, it’s a perverse myth.  North Koreans, like the rest of humanity, are hybrids, survivors of multiple populations that have walked, hiked, and fled across the earth.  And though Kim is probably more interested in consolidating power after executing his uncle and former “regent,” many other regimes have something to fear from recent research on human origins.

You can fool people.  It’s harder to fool nature.

The 400,000 Year Old Man

It’s funny what you find in caves.

One Spanish cave has proven a treasure trove of human fossils.  A recent re-examination of excavated remains found a 400,000 year old thigh bone with “recoverable” DNA.

Work by Svante Paabo and others have discovered many “snippets” of DNA in ancient bones.  The Spanish researchers figured their 400,000 year old man – coming from a site filled with dead Neanderthals – would represent an “early” form of Neanderthals.

Instead, the DNA was much closer to another  disappeared human species – the Denisovans.  Denisovans were originally discovered in a cave in Siberia about 6000 kilometers away, where they lived 80,000 years ago – not all that far from North Korea.

Present day humans have DNA from both Denisovans and Neanderthals.

And that’s from research mainly looking at the 22,000 or so protein coding genes in human DNA.

Human genetics is far more complicated than just DNA.

Epigenetics

It was a long cherished principle of Darwinian evolution – mutations are expressed through genes.  The eighteenth century scientist Lamarck, who believed characteristics acquired by parents in their lifetime could pass them  to their children, was derided in genetics textbooks for well over a century.

Except Lamarck was right.

One recent experiment in mice took naïve mice and made them behaviorally frightened to cherry flavors.

Their kids and grandkids were scared, too.  And the changes could not have occurred through normal mutations of genes.

This is just part of the revived field of epigenetics.  Behavioral characteristics are passed on to offspring in multiple ways.

Because there’s a lot more to genetics than genes.

Junk DNA and Junk RNA

Many years ago I briefly worked for biologists testing the “master-slave” hypothesis of genetic inheritance.  As you can guess by the title, the theory was a non-starter – but it was a good lab tech job for an 18 year old.

The basis of the theory was simple – most of human DNA appeared non-functional.   At least 98% was termed “junk” – repeated strings of garbage sequences.

It turns out that this “garbage” probably contains 2 to 20 million information fragments that control DNA operations – control genes.  One of the “bosses” of genetics was hiding in plain sight.

And some of this control  isn’t even DNA.  Work by James Rinn at Harvard has looked at knock-out mice with long intergenic non-coding RNA.   This “lincRNA” is DNA coded into RNA which is never expressed – as are “normal” genes – into making proteins.

Turns out that if you knock-out this “lincRNA” from mice you also knock out a sizable number of mice.  No lincRNA, no next generation.  The lincRNA sequences – non-gene genes, in effect – are required for survival.

Scientists have become victims of their nomenclature.  They want “genes” to produce proteins that in turn produce brains and bodies.

It’s a lot more complicated than that.

Hybrid Humanity

Recently  black talk show host Trisha Goddard had surprising news for his guest – a neo-Nazi.  Much of his guest’s “DNA” appeared to come from Africa.

What’s true of neo-Nazis is also true of the rest of us – our genetic inheritance comes from everywhere.  Humans have been interbreeding for a very long time.

We’ve long interbreeded with other species – like Neanderthals and Denisovans.  So it’s not such a leap to realize that we’ve been interbreeding with each other – despite our separations by age, ethnic group, tribal group, “race”, nation, and class for a very, very long time.

Which has provided us great strength as a species, and  caused us to rule this planet  – for better or worse.

For human beings like all living creatures are living, regenerating systems of information – powered by chance.

Our systems of information include the genes we normally think of as genes – the privileged 22,000 protein coders beloved of genomics companies. They include the information  mechanisms of epigenetics, our lincRNA, our “junk” DNA.  They include the millions of genes inside the 100 trillion bacteria in our guts, which interact with our genes every second of the day. Ultimately they will probably include many other structures of genetic and physiologic information.  For knowing the DNA sequence of a human being may not tell us much more about that person than knowing how many times Shakespeare used the letters a or s allows us to understand his work.

Structures of information exist that we have not yet glimpsed.

And we must look to the powerful focus of chance on life.  If there had not been so many Ice Ages changing the climate in the last 100,000 years, perhaps the dominant human species on the planet might have been the Denisovans, or the Neanderthals, the diminutive Flores Islanders – or some other population we have yet to discover.

For biological systems of information – like genetics – exist so that life will survive everything and anything thrown at it.  Who knows what chance will do to our future environments –  and to our ultimate survival.

Instead most of us harbor – within each of us – the capacity to survive environments and stresses not yet seen.  Biology is about potential – the ability to take on what cannot be predictably foreseen.

Paradoxically, that has made human beings both more resilient and more alike.  Under the hood we are remarkably similar – far more alike than many of us know.

Or many are willing to acknowledge.