Suppose, in distant future, all living species on earth's surface become extinct...
At this time a alien space shuttle lands on earth surface...
Soon the intelligent aliens who discovered Earth start to study our possessions, trying to piece together the history of their new discovery. They might notice that all of our cookware the pots and pans and plates and bowls and observe that all seemed to be related some how...
Over time, the bowls evolved into plates and coffee cups and stainless-steel frying pans. Eventually, the aliens would create compelling charts showing how the dishes evolved…
Some scientists would be bothered by the lack of intermediate dishware species... but they would assume it to exist somewhere undiscovered…
[This is addressed to commenter]
The problems with your thought experiment are the following:
- Your aliens do not know whether this planet supported life form or not. They can’t differentiate life from non-life. Whereas, humans know that this planet supports life forms and they know life from non-life when they see one – however old that skeleton is – they know if that being was once walking this planet. No human would confuse an artifact with a skeleton.
- Your aliens do not know if a pot evolved into a pan or vice versa. However, humans know which one came first and which one came later. Fortunately for human scientists, nature gives clues – like the rings of a tree which tells them its age in years, fossils reveal their age through different layers of sedimentation. Radioactive dating and other techniques further help in ascertaining the dates. Therefore, if there are fossils at different layers, it is clear that the one at the bottom came first, and then one at the top came later – sometimes after millions of years.
- Your aliens do not know if a beak comes with a pot or pan or a kettle. Human scientists know whether a mammoth has a tusk or not. When they make such an assertion – that a mammoth has a tusk – it does not sound ridiculous because current generation elephants carry those tusks and there are many similarities between elephants and mammoths.
When humans look at fossils, they need to make sure they are the remains or traces of living beings. They do not classify utensils, artifacts made of wood or metal or rock, construction material, modes of transportation, etc, as fossils. How do they know which ones belong to living beings and which do not?
Since they are human, and live on earth, and are familiar with living beings on earth, they are able to say which one belongs to living beings and which ones are just plain and simple rocks. Dinosaurs, shells, prehistoric living animals, etc, all give enough signals to suggest whether they were living beings or not. Skulls, rib cages, bone structures of dinosaurs are not radically different from the skulls of other reptiles of current generation. ‘Fossilized’ pots and pans do not have a contemporary life that supports the theory that they could be living beings. Humans would discard pots and pans and not count them as possible life forms.
Though humans looked at bones and fossils for quite some time it was only in the last two hundred years that we have begun to suspect that there could be natural adaptation. It is not easy to comprehend evolution because it occurs over millions of years. So, how did we start to come up with such a ridiculous proposition that animals and plants evolve, and why did the skeptical scientists who have proclivity to discard every ridiculous theory came around to accept it?
When Charles Darwin visited different continents and island on his voyages, he saw various animals, platypus, tortoises, platypuses, etc, which showed slight variations over various distances – as if the Nature had created two different animal species but closely resembling each other. He also observed fossil bones at the same location of completely another species that has gone extinct but closely resembling the existing species.
With more discoveries, it was clear that earth was walked by certain animals which have gone extinct. Mammoths, saber-tooth tigers, mastodons, were all living beings that walked earth but are no longer seen. Some mammoths, with complete carcass were uncovered from frozen lands, preserved in the ice. So, they know they were not making up things putting together utensils, spoons and pots to imagine living beings, but in fact looking at real animals that once walked earth.
The biologists of Darwin’s time unearthed skeletons of gigantic sloths and hippopotamus-sized armadillo that have gone extinct. Since humans knew the existing sloths and armadillos, and these bones were much bigger than the current generation ones, they surmised these extinct species may have been ancestors of the existing species. How did they know if they evolved or if they coexisted?
While it was clear that certain animals go extinct, Charles Darwin observed different species of an animal slightly different from another but with the same ancestor at both places, suggesting these two different species evolved from the same ancestor.
Enough evidence has come about recording small mutations and adaptations within the recorded history of man to further suggest that Evolution is taking place right now but at a pace that is quite slow for humans to comprehend within a generation.