Ridiculous. All that is necessary is to show that man can be traced back to a proto-human primate, which has been done. With that information and the reptile to mammal sequence, evolution is shown to span higher taxa. Your insistence on every little step being shown is disingenuous. Using your logic we would have to observe every number between 1 and 10200 before we could trust that 10200 can actually be relied on. For all we know, integers follow different rules above 10199.
"Using your logic we would have to observe every number between 1 and 10200 before we could trust that 10200 can actually be relied on. For all we know, integers follow different rules above 10199."
Your analogy does not apply.
The basics premise of mathematics is based on definition, not theory. You are confusing definitions and theories.
Something which is defined is ALWAYS constant with no chance of changing. A theory is based on observations, and is only valid as long as no one produces an exception to the data which spawned the theory.
A scientific rather than math related analogy would be that we would have to observe the behaviour of every rock that has ever been suspended in mid-air, and also every rock that ever will be suspended in mid-air to trust that rocks suspended in mid-air do fall.