odysseus2000 wrote:hallucigenia:
No, humans were not created by aliens.
There are various theories, typified by Fred Hoyle's panspermia, of a primitive form of life - think something like a bacterial spore - arriving on earth via comet dust or meterorites, and then all of life on Earth evolved from that starting point. But that's a long way from "aliens creating all life on earth in their own form", it certainly doesn't require the involvement of anything with consciousness
It is just another theory put about to explain the huge difference between humans & chimpanzees. The argument goes something like how can humans be so much more capable than chimps when humans are very similar in dna etc. So some have postulated that humans come from a genetically modified earlier monkey & that Neanderthals etc were other less successful experiments in genetic modification.
I have been told several times that this is totally impossible, but when I ask how can anyone know I usually get back it’s obvious, but that tells me nothing, but perhaps you can put forward a convincing argument.
Well the nature of science is that you can never "prove" things definitively - the fact that 100 apples fall from a tree makes it a high probability that the Newtonian model of gravity is correct and the earth is attracting the apples through gravity rather than say them being repelled by the sun - but as scientists you accept that your view of the probabilities may change in the light of new evidence. And in fact although Newton's model served us pretty well for centuries, more recent evidence suggests that things may be a bit more complicated than that and so the theory adapts to incorporate ideas on quantum gravity etc.
So it is with evolution - you're constantly looking for the high-probability explanations, even if you can't definitively rule out the theories that are the equivalent of apples being repelled by the sun. But Occam's Razor applies - in general a simple explanation is to be preferred over a complicated one invoking unknown God-like beings that are capable of doing genetic engineering.
But rather than have me reinvent the wheel, I strongly suggest you read a suitable book to get up to speed on the basics of how evolution works, as there's not much point in starting this discussion until you do. Something like Steve Jones'
Almost Like a Whale is a good place to start.
Also you need to give chimps a bit more credit - they are capable of fairly sophisticated social interactions, tool use, have elements of self-awareness, language and so on. They're often compared to having roughly similar capabilities to humans at the age of 4 or 5, but in some aspects they are some way ahead of children of that age. I really recommend
Jared Diamond's (The Rise And Fall Of) The Third Chimpanzee to get a better appreciation of what chimps are capable of - if you have the idea that they are somehow fundamentally different to humans then you'll make mistakes when considering their evolution.
Likewise their underlying biology is pretty similar, from how their genes work to the kinds of neurons involved - there's no "step-change" involved, it's not like we have dilithium crystals in our heads and chimps don't.
So if the underlying biology is similar, and the observed "intelligence" etc is on a spectrum with humans, then Occam says that any observed differences are down to the underlying biology varying on a similar kind of spectrum - things like the number of connections per neuron, or relatively small increases in the number of neurons. Remember that - whilst again caveating that genomic comparisons get complicated - 1.6% may seem a small difference between humans and chimps but on 3 billion "letters" of DNA that amounts to nearly 50 million differences.
And just one letter difference can make a huge difference to what you see, as some genes are "control" genes that affect the number and distribution of entire "packages" or "modules" of genes, so if you get a single letter mutation in the control genes you can get dramatic changes like flies with legs growing out of their heads, or XY "men" turning into anatomical women.
But do read the Jones and Diamond books - they're a little old now so there may be better recent equivalents, but those are two that I've read myself.