Re: Θεωρια της εξελιξης: Μια ετοιμοθανατη θεωρια?
Δημοσιεύτηκε: 09 Απρ 2019, 14:19
EVIDENCE FOR EVOLUTION - Evolution Makes Testable Predictions.
The defining characteristic of all scientific knowledge, including theories, is the ability to make falsifiable or testable predictions. In the 1950's when it was discovered that humans had 23 pairs of chromosomes (one from each parent), whereas the other great apes, chimpanzees, gorillas and orangutans had 24 pairs, creationists were ecstatic, thinking they finally had evidence to counter common ancestry.
[Chromosomes are packages of DNA that form during mitosis and meiosis.There are two sets, one inherited from each parent. Other Great Apes have 48 chromosomes (24 pairs) (1n=24, 2n=48) whereas humans have 46 chromosomes (23 pairs) (1n=23, 2n=46)]
Evolution made a testable prediction; That somewhere in the human genome we should find evidence of cromosomal fusion. In other words, we should be able to find a human chromosome with the remnants of extra telomeres and centomeres.
Since the loss of all the genes in a chromosome would have been fatal to any species, scientists reasoned that IF the Theory of Evolution was correct about common ancestry, one of two things must have occurred. Either two chromosomes had fused in human's evolutionary past, OR chromosomes had split in the other apes. Using 'Occam's Razor' or the "law of parsimony" which states that among competing hypotheses, the one with the fewest assumptions should be selected (Simply put, it means that the simplest explanation is most likely the correct one), the most likely event was chromosome fusion in humans.
Normal chromosomes have a centromere and ends capped with telomeres. It was reasoned that IF two chromosomes had fused, evidence for such an event would be found in a chromosome with two centromeres and teleomeres where they did not belong. That is exactly what was found in human chromosome 2 (chromosomes are numbered by length). It was subsequently discovered that chimpanzee chromosomes 12 and 13 (for comparative purposes designated as 2A and 2B or 2p and 2q) contained the same genes as human chromosome 2 and if placed end to end the positions of those genes matched those of the human chromosome. Those chromosomes in the other apes also lined up in a similar fashion. The fusion event has been confirmed. In just the last few years science has gained largely complete genomes of two other human species, those of Neanderthal and Denisovans. We see that same chromosome fusion in their genomes as well, indication that the fusion event took place in a common ancestor.
As previously stated, the defining characteristic of all scientific knowledge, including theories, is the ability to make falsifiable or testable predictions. The greatest test of ANY scientific theory is in its usefulness as a predictive tool. In this case, as with others, the Theory of Evolution has performed beautifully.
References:
https://ghr.nlm.nih.gov/chromosome/2
www.pnas.org/content/pnas/88/20/9051.full.pdf
https://biologos.org/blogs/...to.../den ... e-2-fusion
www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html
The defining characteristic of all scientific knowledge, including theories, is the ability to make falsifiable or testable predictions. In the 1950's when it was discovered that humans had 23 pairs of chromosomes (one from each parent), whereas the other great apes, chimpanzees, gorillas and orangutans had 24 pairs, creationists were ecstatic, thinking they finally had evidence to counter common ancestry.
[Chromosomes are packages of DNA that form during mitosis and meiosis.There are two sets, one inherited from each parent. Other Great Apes have 48 chromosomes (24 pairs) (1n=24, 2n=48) whereas humans have 46 chromosomes (23 pairs) (1n=23, 2n=46)]
Evolution made a testable prediction; That somewhere in the human genome we should find evidence of cromosomal fusion. In other words, we should be able to find a human chromosome with the remnants of extra telomeres and centomeres.
Since the loss of all the genes in a chromosome would have been fatal to any species, scientists reasoned that IF the Theory of Evolution was correct about common ancestry, one of two things must have occurred. Either two chromosomes had fused in human's evolutionary past, OR chromosomes had split in the other apes. Using 'Occam's Razor' or the "law of parsimony" which states that among competing hypotheses, the one with the fewest assumptions should be selected (Simply put, it means that the simplest explanation is most likely the correct one), the most likely event was chromosome fusion in humans.
Normal chromosomes have a centromere and ends capped with telomeres. It was reasoned that IF two chromosomes had fused, evidence for such an event would be found in a chromosome with two centromeres and teleomeres where they did not belong. That is exactly what was found in human chromosome 2 (chromosomes are numbered by length). It was subsequently discovered that chimpanzee chromosomes 12 and 13 (for comparative purposes designated as 2A and 2B or 2p and 2q) contained the same genes as human chromosome 2 and if placed end to end the positions of those genes matched those of the human chromosome. Those chromosomes in the other apes also lined up in a similar fashion. The fusion event has been confirmed. In just the last few years science has gained largely complete genomes of two other human species, those of Neanderthal and Denisovans. We see that same chromosome fusion in their genomes as well, indication that the fusion event took place in a common ancestor.
As previously stated, the defining characteristic of all scientific knowledge, including theories, is the ability to make falsifiable or testable predictions. The greatest test of ANY scientific theory is in its usefulness as a predictive tool. In this case, as with others, the Theory of Evolution has performed beautifully.
References:
https://ghr.nlm.nih.gov/chromosome/2
www.pnas.org/content/pnas/88/20/9051.full.pdf
https://biologos.org/blogs/...to.../den ... e-2-fusion
www.pbs.org/wgbh/evolution/library/07/3/l_073_47.html