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ikefalcon t1_j508nej wrote

Reply to comment by VictoriousEgret in Given that reproduction is difficult or impossible when both animals have different numbers of chromosomes, how did so many species evolve to have so many different numbers of them? by MercurioLeCher

As the previous commenter said, human chromosome 2 has nearly identical sequences to chromosomes 2a and 2b in the other great apes. It’s believed that human ancestors like Neanderthals had 23 chromosome pairs like humans.

Also, chromosomes usually have 1 centromere (center link between pairs of chromatids) and 2 telomeres (basically end caps of the chromosome). Human chromosome 2 has a vestigial (unused due to no longer being needed) extra centromere and 2 vestigial telomeres found inside the chromosome sequence.

This is pretty good evidence that there used to be 2 chromosomes before they fused together.

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wheatgrass_feetgrass t1_j50lv6a wrote

>Human chromosome 2 has a vestigial (unused due to no longer being needed) extra centromere and 2 vestigial telomeres found inside the chromosome sequence.

Goddammit that's cool.

I can't be sure of it quite yet, but I have a feeling sequencing the entire genome is the single greatest human breakthrough in my lifetime. I was in middle school when my science teacher told us it had been done for the first time. When I was in college I toured a sequencing facility where it was being done for outrageous cost per sequence on machines bigger than my house. Last year I got my own DNA fully sequenced, every single base pair, for about two day's wage.

Reading your own ancient programming code letter by letter is a weird, almost disassociating experience.

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