We share half our DNA with a banana – does that make you half a banana? No, of course not! Everything on the planet shares at least a quarter of their DNA with everything else. So how come we look so like chimps and not bananas? Well, within the human genome, you will find a tiny part (2%) that codes for proteins – these genes are what we have in common with chimps, so, about 95% of this 2% defines the relationship between humans & chimps and the theory is that the more this gene sequence corresponds between creatures/organisms: the closer the relationship on the evolutionary family tree.
NOTHING COULD BE FURTHER FROM THE TRUTH…
… the part that codes for proteins and builds those unique bodies, i.e. a banana vs. a baboon (the blue-print in your genes), is only 2% of the whole evolutionary story – it is the other 98% of the genome that used to be called junk because it did not code for proteins & we therefore thought is was useless, that turns out to be not so useless after all. Furthermore, of the 2% that codes for proteins we share some stretches of these with bacteria and even cows and snakes share some specific genes and they certainly aren’t supposed to be that directly related!
And on that note:
For example, looking at general studies dealing with the direct common descent model and finding that it may not fundamentally be correct is reflected in the quote excerpts below, taken from a scientific study titled: Evolution of Vertebrate Brains by Prof. A B Butler, George Mason University, Fairfax, VA, USA :
…both evolution and embryological development proceed from the general to the specific. In regard to evolution, the common ancestor of all vertebrates, for example, gave rise to the radiation of jawless vertebrates on the one hand and to that of the jawed vertebrates on the other; lampreys did not give rise to hagfishes.The common ancestor of tetrapods gave rise to amphibians on the one hand and to amniotes (reptiles, birds, and mammals) on the other; neither frogs nor newts gave rise to reptiles,birds, or mammals. Among amniotes, mammals actually appear in the fossil record before reptiles; reptiles did not give rise to mammals any more than mammals gave rise to reptiles…
In regard to embryological development, it likewise generally proceedsfrom the general (common ancestral features) to thespecific (specializations of the taxon)…
….That brain enlargement and elaboration hasoccurred four times independently presents a verydifferent reality of how brain evolution has operatedthan is perceived in the widely held folk-beliefof a sort of scale of nature, or Scala Naturae, thatranks all vertebrates along a simplistic scale. Instead,the picture now appreciated is a much more sophisticated and fascinatingone in terms of both evolutionary history and the mechanismsby which it has proceeded…
Just as mammals diverged from the stemamniote stock, so did the sauropsid line that gave risefirst to reptiles and, subsequently, birds, which actually are a specialized group of reptiles, just as are the other extant groups of this major taxon.
Butler (2009 57-64)
In other words, this and an increasing number of studies akin to this one dealing with other features (as the article points out) are seriously beginning to challenge our certainty of the common ancestral model of species descent based on genetics and/or physical features. Instead, it is proposing quite a distinct scenario, based upon the general direction of the evidence, and that is that the main taxa (major groups of vertebrates/amniotic groups for example) reflect a less linear and direct descent pattern of evolutionary speciation as our current model assumes, but rather form of SHARED (COMMON) ANCESTRAL CONDITION from generalist forms to more specialised groups and thereby diverged from these commonly shared ancestral body plans.
For more detail on this see more recent related article on this blog:
Essentially, a great deal of our presumption that genes R-Us thinking is a historical artifact and derives from an assumption that the closer the shared blueprint of features – homology/homoplasy: the more related a species and the closer, in time, was its ancestral split in the family tree. This is assumption – synonymous with direct common descent.and this defined (historically) our terminology which, led to the fossil record being interpreted in a particular manner and this led ultimately bolstered the belief that the common code of life works in much the same way: the closer the shared coding: the closer the ancestral relationship. And in the end, this leaves us with a ridiculous thought: Well, if we share almost half of our genes with a banana, does this make us half bananas?
Now, looking again at this mere 2% of our human genome in a rather different light, you know: the genes which we have been told run everything, they are selfish, they cannot be changed, once you are born, you are stuck with those fixed and genes and there ain’t nothing you can do to change them. Furthermore, you were told that your body is a blank sheet and you only inherit what your parents had in their genes (their chromosomes) and nothing they ever did in life could change that. AGAIN, NOTHING COULD BE FURTHER FROM THE TRUTH.
All of the following statements are fully supported scientifically and are updated and detailed within the forthcoming book: Evolution: A Scientifically-Guided Thought Experiment: By Other Means…?
It is not my own personal theory: but the culmination and what naturally emerges by bringing all of scientific alternatives together in one place, in the light of our most up-to-date understanding of biological complexity and seen within their historical context.
SUMMARY OVERVIEW of A RATHER DISTINCT EVOLUTIONARY PATTERN EMERGING
Well, this turns out to be something to do with horizontal gene transfer (HGT), akin to direct hybrids of very distinct species that we thought only messed up the evolutionary tree at the base in the microbial world, but apparently, it goes all the way up and outward to every branching tip. Then, there were all those microbial mergers (different single-cellular organisms joining forces), seemingly into direct and rather long term mating rituals to form the highly sophisticated life form of multi-cellular eukaryotes (that’s plants and animals and US). Oh, and then the actual seeming ubiquitous hybridisation which went on in the evolutionary past which is turning out to be a serious source for evolutionary (genetic) novelty to feed the vast diversity, the large complete leaps to new and exotic forms and by all accounts, it happened rather rapidly. Essentially, we are all essentially hybrids at some level and this makes finding that presumed long lost cousin or ancient ancestor just a bit pointless.
Now, we have to consider Nature’s wild card in all this and that is those jumping genes that can cut, paste, rearrange genes and delete or create new ones and generally remodel genomes and the result is of course a remodelled organism. Such events are strewn all over our genomes and why we are particularly full of junk compared to many other organisms. All of this of course is in direct response to environmental triggers, but thankfully, due to Nature following natural universal scaling laws of growth, form and function, everything has matured to species level now and we no longer have such dramatic morphs into strange and exotic forms according to the weather.
However, we do have old ancestral programs running and in some instances, it seems that less complex organisms such as plants and some amphibian or reptile/fish types can reactivate these in times of need; growing or regenerating new limbs, losing eyes if living in dark environments, or in case of plants, changing its colour in accordance with its differently coloured environment. How else do you think a sluggy, creeping, leaf munching caterpillar transforms into a beautiful butterfly? It has the exact same genes – its the same creature, yet, when the time is just right (environmentally-triggered) it begins to transform and get its genome entirely remodelled.
These little natural engineering processes of the genome itself at different scales (we’ll assume from the evidence that when species were fairly primitive that these genome makeovers may have been more dramatic than they are today) is orchestrated via epigenetic release of the jumping genes, but more commonly via the expression of conserved genes that stay relatively fixed these days, but how, when and where these are expressed can make a dramatic difference in the end. Just like a dimmer switch, or/and a biochemical ‘on’, ‘off’ switch, a gene is expressed, or not, at certain times and to a particular degree and this accounts for a great deal of species variation. A species can also express the same genes differently according to how tightly or loosely their chromosomes are packaged in the cell.
How else do your genes, which are the same in every cell (pluripotent/stem cells – un-programmed) know what to be when they grow up? They differentiate into different cellular functions to create organ, neuron and bone cells to name but a few highly specialised functions. On another scale, we can say that the species (being organised cellular organisms), as seemingly this evolutionary game is all about natural efficiency and scale, and as cells differentiate into specialised functional colonies enclosed within a massive cellular organ (skin), why can we not call these differentiated and specialised species that due to cellular memory and biochemical signalling: literally (like memory foam) remember what they are going to be when the grow up.
This is the generalist to specialist model via epigenetic/epigenesis (environmentally-triggered/guided) modification within the context of responsive cells as it is factors operating above the genes that ultimately appears to control the meaningful expression/outcome of all of this novel transference of genetics across every scale of life and ultimately lets those jumping genes explode into action if drastic measures are called for (don’t worry – The Day of the Triffids – a B-Movie from the 50s or 60s if I recall, where the plants get rather large and eat people for lunch instead of the other way around) is not about to become a reality – everything seemingly, has settled down these days, in evolutionary terms, but there is still a little flexibility. This is part of Nature’s scaled underpinnings.
These are just some of the reasons why we look nothing like bananas, yet we share so much of the mere 2% of DNA that codes for proteins – all life shares the code, it is just how it is expressed/remodelled and what it with over the great course of time. And don’t forget the weather and I suppose once it remembered to be a plant and got practiced at being a fruit and then specialise as a banana, well, it probably just got very good at being a banana and some more complex organisms went on to specialise at acting ‘bananas’ – sometimes…