What They Didn’t Tell You About The Human Genome
What they didn’t tell you about the human genome
Yeah, by now you know the drill: we have Deoxyribonucleic acid (DNA) which is the library of information which contains instructions to make humans. DNA is composed of four base pairs: cysteine, adenosine, triphosphate, and guanine which combine into base pairs of two amino acids: c-g, a-t to make the double helix which forms the backbone of human DNA. Furthermore , we have genes which we supposedly inherited from a long extinct species which was the ancestor of the modern day chimpanzee. However, what if all of this jazz was not completely correct? What if you learned that we have DNA from different species of animals and plants, most notably other species of humans, who lived with our ancestors in the distant past? What would you think? Yeah, well if you’re curious to know more about this, read on!
Did you know that you are not completely human?
Wait, what is that? We are not completely human, what is this nonsense about? Well, it is not nonsense, this premise is based on genetic evidence which scientists and geneticists are gathering as they dissect, splice, and analyze the human genome as part of the human genome project 2000. Indeed, both scientists and geneticists are increasingly discovering that the genetic material which is found in humans at the cellular level may harbor at least 145 genes which have migrated into the human body from ancient single celled organisms, mostly bacteria.
And then there’s the tree of life…
What on Earth is the tree of life, and what does it have to do with the human genome and human evolution? Well it has a lot to do with both because it is the basic model which scientists and geneticists use to describe the story of human evolution in blue print format. The tree of life comes from the Old Testament and was used to describe their more primitive understanding of human evolution. Charles Darwin used this tree as the foundation from which he formulated his ideas which formed the very famous theory of evolution which revolutionized Biology forever.
How does this change our understanding of human evolution?
This is a very good question to ask, and if you asked this question, it means that you are smart and understand the basics of evolution, and most importantly, human evolution! For decades, ever since the great naturalist Charles Darwin first published his flagship book On Origin of Species which discussed the basic ideas and supporting evidence which formulated the theory of evolution, scientists and geneticists have assumed that the tree of life has had perfect branches of lineage whose genes were passed down through the generations perfectly and neatly through vertical gene transfer. However, these new findings are having scientists and geneticists rethink and model this tree, which is in turn dramatically redefining and reshaping their understanding of the theory of evolution! The new model of the tree of life resembles that of a winding tree with roots which are grossly intertwined everywhere, the same is true of its branches. Scientists and geneticists are also realizing that the evolutionary history of humans has been a sloppy and winding one with genes jumping from different species to humans in a messy journey throughout the millennia!
How this is changing the way scientists and geneticists understand the basics of human evolution:
So how does this change the way scientists and geneticists understand how we got to be on Earth, and our basic story of evolution (which is essentially our basic story of survival)? Well it totally turns it on its head because it means that horizontal transfer genes has been occurring in the human genome ever since the first human (species: homo sapiens sapiens) first set foot on Earth’s soil somewhere in what is now sub saharan Africa about one hundred thousand years ago. Previously scientists and geneticists thought that this kind of gene transfer (horizontal transfer) only occurred in simple, single celled organisms, you know like bacteria and prokaryotes. They had no idea that horizontal gene transfer occurred all of the time in more complex species of animals – yes this happens all of the time in other species of mammals, insects, reptiles, birds, plants, humans, etc…
More about genes from other animal species which now live in human DNA…
As mentioned earlier, scientists and geneticists are taking apart the human genome and really analyzing it. And what they have been finding out is literally put shocking them because they are finding out that approximately 31,000 genes in human DNA are shared with other species – most being from chimpanzees. However, about 300 of these 31,000 genes are from species of animals, plants, insects, reptiles, birds, etc…they are definitely not from chimpanzees.
Did you know that the human genome stands in a class of its own?
Now what in the heck does that mean? Well it means that humans have genes, about 240 of them, which NO OTHER living species, or species which has ever lived on Earth has! This includes genes which code for our voice box, and vocal cords which are unique to humans. It also includes genes which code for our ability to stand upright. It includes genes which contain information to design our opposable thumbs which make human civilization possible (imagine trying to manipulate the tools needed to create the blueprints for the Colosseum without them!)
And as a final note
What scientists and geneticists are finding out about the human genome is both is both shocking and amazing them. For one thing, they are finding out that genes are amazing pieces of information which contain the blueprint of life on Earth and appear to be interchangeable between and among different species on Earth through the process of horizontal gene transfer. They are also finding out that the story of human evolution, and that of evolution in general, is not a neat process of genes being transferred from one generation to the next in a very simple process. Instead, it is a messy and complex process which involves the swapping of genes between and among the different species on Earth for millions of generations. And as humans continue to evolve, this process is ongoing. This is leading scientists and geneticists to question the true origins of the human species. More on that in another article!