He was both right and wrong . Wrong in that Evolution can only come about over long periods of time , thousands , millions of years . Changes can come about in a single generation .
Please quote the part where Darwin wrote that evolution can only come over long periods of time etc. I assume you've read Darwin's work.
Can it really? While a mutation can occur over a single generation of a single line, in order for it to establish itself as a step in evolution it has to spread throughout the population. It will take several generations before this new trait becomes significantly entrenched. Evolution works on populations, not individuals.
Here are the fundamentals of his thesis: 1) Organisms reproduce more than strictly necessary to ensure continuity of a species. (Specifically, in organisms that reproduce sexually, each female typically has more than two offspring.) 2) Organisms inherit traits from their parents. These are encoded in their genome and they then pass those traits on to their offspring. 3) Offspring sometimes differ from their parent(s). This may be due to a new combination of genes (in sexual reproduction) or mutation (in all organisms.) 4) Those differences are harmful, benign or (very rarely) advantageous to the organism. 5) The organisms that experience harmful changes die before they reproduce. This reduces or eliminates that genotype in the population. However, because of 1), this does not cause extinction. 6) The organisms that experience beneficial changes have more offspring than average. This increases the prevalence of that genotype in the population. 7) In time that genotype becomes widespread. So yes, a change can come about in a single generation to a single organism. However, to spread throughout the population takes dozens to thousands of generations. (Note that "rapid" in evolutionary term can mean hundreds of generations - which can range from weeks in bacteria to millennia in mammals.)
A compelling argument can be found in the rare beneficial mutation in the DNA of the human hominid ancestor, which produced homo sapiens (smart ape). Human Chromosome 2 is a fusion of two ancestral chromosomes Alec MacAndrew Introduction Please Register or Log in to view the hidden image! Conclusion http://www.evolutionpages.com/chromosome_2.htm IMO, this mutation resulted in the increased size and functionality of the human brain. It seems that by evolutionary standards humans are smarter than necessary and not always to our own benefit. The remaining hominid population have followed a normal evolutionary trajectory and while we share many similarities, our increased brainpower has made man the dominant land dweller (except for the insect)......Please Register or Log in to view the hidden image!
