The fact that you don't know why, actually explains quite a lot about your complete ill-understanding of biological science.
It's a good analogy, because if we apply YOUR type of reasoning to crime scene investigation, then it becomes IMPOSSIBLE to EVER convict ANYONE of ANYTHING if there are no eyewitnesses.
And what makes the irony meter explode about that, is that eyewitnesses ("personal testimony") is not at all reliable when it isn't corroborated with actual evidence that you are trying to toss out the window.
Wait, so your objection to crime scene investigation is that.... humans can make mistakes and lie?????
But when you only have "human testimony" to defend your bronze-age beliefs - then suddenly it is okay???
The hypocracy is mindblowing.
Right, because eyewitnesses do not make mistakes, aren't guided by emotion and are unable to lie.




Right, so let's look at a hypothetical scenario and apply your reasoning to it and see what happens.
A murder took place. A body is found with a knife sticking in the back. The knife has fingerprints of person A. On the body, DNA is found from person A. In the home of person A, a shirt is found with bloodstains of the victim. A speeding ticket is uncovered from person A, dating to half an hour after the murder close to where the murder took place. Person A has no alibi. The victim owed person A some money - so there is a possible motive.
However, a person claiming to be an eyewitness says that he saw person B kill the victim. Nothing else but this "testimony" points to B. Without the testimony, B's name wouldn't even have come up.
So YOU would discard all the evidence and convict B?
If you do, then you are unfit for jury duty.
If you don't, then you just contradicted your own nonsense.
Good day.