For most of human history people took it for granted that every form of life was a unique creation. In general this meant that each ‘kind’ mated with its own kind to produce offspring. For our ancestors that was patently obvious. Lions did not mate with chimpanzees and so on. The differences between each plant and animal were seen as proof that a creator had been hard at work making all these different living creatures with a unique unchanging template for each. The differences were more than just superficial. Organisms were different ‘down to the bone’ with no possibility of diverse species interbreeding. And once created the templates were ‘set in stone’ with no changes possible. After all a powerful creator had willed it so. Perhaps it would have been better if that were really true.
But the reality is there was likely only one creation event. One can hypothesize about just who or what was the instigator of that event, but biology and genetics backed up by chemistry and paleontology tell us that all living organisms on Earth have a single common ancestor, a single celled creature with the ability to make copies of itself and its genetic ‘code’ through the replication of DNA. This primordial process continues today in every living organism at the cellular level. Every living cell no matter from what living organism you might investigate including all plants and animals have the same engineered plan based on DNA. The difference is only the way the genetic material in each cell is arranged and the complexity. Also inherent in each cell is the potential to make subtle changes through ‘mistakes’ in the replication process or outside influences. Almost all of those changes (mutations) are harmful or irrelevant but a very few give the organism a slight survival advantage providing the basis of biological evolution and species diversification.
The wonder isn’t that all life on Earth has evolved from that ancient single cell ancestor, but that the single living cell evolved in the first place. The broad strokes of the panorama of species change are fairly well mapped out through Natural Selection and Variation Within Species. But although modern science can artificially construct the chemical building blocks of living creatures and we find those molecules occurring naturally even in the distant Cosmos, it cannot take those necessary chemical pieces and put them together to make a fully formed living cell. At least not yet.
The basic similarity of the structure of DNA and genetic codes of all living organisms has opened the door to the possibility of actually mating a lion and a chimpanzee at least at the ‘test tube’ level. The technology known as gene-splicing or editing can exchange, replace, or remove genetic instructions between different unrelated life forms. As mentioned in previous columns, this is already happening to create hybrid organisms, especially for agricultural purposes. But there is no reason the same technology couldn’t be used to combine and manipulate any genetic material from any organism.
Suppose a genetic instruction is discovered in the human genome that increases the risk of developing cancer, or deformities, or that might produce other deleterious effects. One could see if that bit of genetic material could be removed say from a female egg by gene editing how that might represent a positive breakthrough in medicine. We might also discover a genetic instruction in another animal that counters the aging process (the African mole rat and water bears come to mind) that could be grafted onto human DNA thus creating the same effect. Or finding the specific genetic instructions that allow some animals to grow back severed appendages and adapting those instructions to humans. Many other organisms have characteristics we might like to acquire and it is at least theoretically possible for us to do so through gene editing and splicing. Very recently human and chimpanzee DNA were successfully experimentally combined. Science has taught us that the ancient creation stories were way off the mark, but now we face a dilemma.
The question should be: How far down this road (or rabbit hole) do we want to go? In the ancient Egyptian religion many of their gods were part human and part animal. That was unquestioned truth to them, but mythology to us. (Ancient religions and folklore include dozens of human-animal hybrids, a subject for another article.) As it turns out, we now have the capability to turn that mythology back to truth, and should be mindful of the one undisputed law as we plunge down that road: That of unintended consequences.