On Evolution

I ran into a claim that are no observations of evolution.

There are observed changes in allele frequency over time. That is evolution. If one wants a very specific example, then consider lactose tolerance in adult humans.

Most people become lactose intolerant after reaching adulthood. But about 10,000 years ago a mutation occurred in Northern Europe that allowed adults to digest lactose. Since the mutation coincided with the development of cattle domestication and dairy farming, it provided a survival advantage. 

The ability to digest lactose into adulthood is also a dominant trait. This means if you inherit one modified gene from either parent, you are likely to be lactose tolerant. 

So because of the spread of dairy farming and the mutation being a dominant trait, lactose tolerance in adults has spread through Europe, into North America, parts of Asia and the Middle East. Today about a third of adults are lactose tolerant 

That’s what’s called observed evidence.

A Scientific Theory explains observed facts. The observed fact in my lactose tolerance in humans description above is that lactose tolerance is spreading. The explanation, the theory, of the spread is that with the growth of dairy farming it has a survival benefit and it is a dominant trait.

The “theory” is based upon the evidence available. Tomorrow someone could discover a new piece of evidence that would supply a better explanation of the observed fact and become the new theory.