Illuminating Reality

One hundred fifty years ago today, Charles Darwin published one of the most important publications in all of Science – “On the Origin of Species.”  Darwin had been developing his scientific theory of evolution by natural selection for a number of years based on evidence gathered from around the world, particularly his excursion in the Galapagos Islands.  If his theory was correct, it would challenge the very fabric of our understanding of life on Earth, something that he wisely didn’t take too lightly in the 17th Century.

In the decades that followed, Darwin was attacked and ridiculed particularly by the Church of England, but in the scientific community he was supported and eventually lauded for his work.  But for the man himself, who was once firmly entrenched in a religious life, the results of his work led him to more secular beliefs which deeply conflicted with those of his wife.  It’s ironic that in many ways Darwin was exploring biology to help confirm his religious beliefs yet in the end the results he could not deny ended up pushing him to adopt agnosticism.

So as much as “On the Origin of Species” is a scientific triumph, a scientific theory that has become the foundation of modern Biology and been confirmed by many independent fields (genetics, for example), it is also seen as a key publication in the eyes of the atheists, agnostics and secular humanists.  They see it as the first major attempt to push back against theology in the post-Enlightenment era.

I think Richard Dawkins summed up the importance of Darwin’s book when he wrote, “Living organisms had existed on earth, without ever knowing why, for over 300,000 million years before the truth finally dawned on one of them. His name was Charles Darwin.”

Like every other human,  I came from Africa ultimately.  But anthropologists have long known that early humans branched off as they left Africa and spread throughout the world.  My particular lineage takes my ancestors out of Africa and through the Middle East.  At this point, roughly 40,000 years ago several groups split off – one going south into India and eventually making its way to Australia, while another ends up in China.  My ancestors, like most Europeans, moved west and populated most of Europe.  During the last ice age things got so bad that my ancestors migrated south into a pocket of southern Spain known as the Iberian Refugium.  Once the glaciers receded they moved north and repopulated most of western Europe.

The marker in my Y-chromosome connects me to 70% of the men in southern England and as much as 90% of men in Spain and Ireland.  Pretty cool, huh?  How do I know this?  Because I participated in the Genographic Project being run by National Geographic and IBM.  It’s an ambitious program to process a wide variety of genetic samples from people from around the world and create the ultimate database of human genetic history.

You can see a short video of the project in action here…

How do they do it?  By sequencing DNA and looking for genetic “markers.”  DNA for the most gets combined by parents to produce a hybrid form in offspring – this is why we have similarities with our parents but aren’t carbon copy duplicates.  Mitochondrial DNA is a small piece of the puzzle that has the unique quality of being passed down by mothers and doesn’t really change, in essence creating  a simple note that can be tracked through populations.

Alice J. Dunn has a more detailed explanation:

Scientists who trace modern human origins often talk about a special kind of DNA, mitochondrial DNA (mtDNA). But do you know what mitochondrial DNA is? And do you know what mitochondria do? Mitochondria are tiny structures found within the cell that resemble grains of rice. They produce the energy that cells need to function, and they have their own small complement of DNA, containing just 37 genes in humans. Compare this to the human nuclear genome (the entire set of genetic instructions found within the nuclei of all the cells), which contains some 30,000 genes. But mitochondrial DNA is especially powerful for studying the ancestry of modern humans. While the nuclear genome is reshuffled with each new generation as the father’s and mother’s DNA recombine, mitochondrial DNA is passed directly from a mother to her children. As a result it preserves patterns of ancient markers that thelp scientists map the path modern humans have taken around the world.

So by collecting samples and looking for these mtDNA markers, scientists can identify and track the lineage of a person along a well established migratory path from Africa.  Over the years it’s been established that early humans migrated out of Africa and many groups have branched off from those initial groups, as seen in the map below:

Which one are you a part of?

Yesterday Elizabeth H. Blackburn, Carol W. Greider and Jack W. Szostak won the prize for discovering telomeres and telomerase.  At first glance you may wonder “what the hell does that mean?”  Well, they discovered important structures in chromosomes that sort of acting like an “end cap”, preventing individual chromosomes from connecting.  There was a bit of a mystery as to their function though and these scientists were able to show that they had a protective function, helping to prevent aging in the cell.  This opened the door to advancements in cancer and disease research because it helped identify telomere defects as the source in some cases.

But another important aspect of their discovery was that these telomeres could act as genetic markers and one of the greatest mysteries in human evolution is centered around chromosomes.  In a nutshell, we share a common ancestor with chimpanzees, yet while we have 46 chromosomes, they have 48.  We can’t have lost a pair of chromosomes; that would be lethal.  So Evolution predicts that for us to have 46 chromosomes, a pair must have fused.  Now this is where the telomeres become important:  by counting the telomeres in the human genome, biologists are able to identify which chromosome fused if any.  Ken Miller explains this in more detail…

Richard Dawkins has a new book out on Evolution called “The Greatest Show on Earth.”  Unlike his previous books where he tends to explain evolutionary theory as well a pick apart anti-evolutionary claims, this one seems to be more geared at laying out the mountain of evidence that supports the theory.  This is a welcomed change of tone as I think his attitude over the years as been too aggressive in attacking those who attack Evolution.  While I think it’s important to counter the false statements made attacking Evolution as well as the vast misinformation coming from Christian conservative circles, I find far too many people out there are rather ignorant of the evidence, regardless of where they actually stand on the subject.

With Science in general I think it’s important for us to be more inclusive to the public but also put the cards on the table and explain why we believe a theory is correct.

The evolution of whales I’ve found is one of the most remarkable stories in biology.  When you think about it, whales (like other Cetaceans) are unique in that they are ocean dwelling mammals with more in common with us than fish.  They breathe the air like us and have skeletons very similar to other mammals, but it’s in those skeletons that has long hidden a secret to their past and how they came to be the creatures we know.  It seems natural to believe that whales have always been ocean dwelling creatures, but fossil evidence over the last decade or so has confirmed that in fact they were land dwelling mammals that returned to the sea.  Check out this video for a detailed explanation…