It’s a well-known fact that humans have 23 pairs of chromosomes- 46 chromosomes in total. However, chimpanzees have 48 chromosomes, as do the other ‘great apes’. Why is this? Well, it centres around human chromosome 2.
Sources for this episode: 1) Fullick A., Locke, J. and Bircher, P. (2015), A Level Biology for OCR A. Oxford: Oxford University Press. This is where I originally learned the chromosome numbers of horses and donkeys; however, I don’t have access to this book at the moment due to COVID. For an alternative source, see: Rodriguez, M., Understanding Genetics, The Tech Interactive (2007), Chimeras, Mosaics, and Other Fun Stuff: Why can’t mules breed? I understand that a horse and a donkey make a mule but why can’t 2 mules have a baby mule? (online) [Accessed 06/06/2021]. 2) IJdo, J.W., Baldini, A., Ward, D. C., Reeders S. T. and Wells, R. A. (1991) Origin of human chromosome 2: an ancestral telomere-telomere fusion, Proceedings of the National Academy of Sciences of the United States of America 88(20): 9051-9055. 3) Willey, J. M., Sherwood, L. M. And Woolverton, C. J. (2017), Prescott’s Microbiology, 10th edition (International Edition). New York, McGraw-Hill Education. 4) Young, W. J., Merz, T., Ferguson-Smith, M. A. and Johnston, A. W. (1960), Chromosome Number of the Chimpanzee, Pan troglodytes, Science 131(3414): 1672-1673. 5) Author unknown, Wikipedia (date unknown), Chimpanzee genome project (online) [Accessed 02/06/2021]. 6) Author unknown, WWF (date unknown) Great apes (online) [Accessed 06/06/2021].