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A humanized mouse is a genetically modified mouse that has functioning human genes, cells, tissues and/or organs. [1] Humanized mice are commonly used as small animal models in biological and medical research for human therapeutics.
For example, neutral human DNA sequences are approximately 1.2% divergent (based on substitutions) from those of their nearest genetic relative, the chimpanzee, 1.6% from gorillas, and 6.6% from baboons. [10] [11] Genetic sequence evidence thus allows inference and quantification of genetic relatedness between humans and other apes.
Humans share about 99% of their genome with chimpanzees [61] [62] (98.7% with bonobos) [63] and over 90% with the mouse. [60] With so much of the genome conserved across species, it is relatively impressive that the differences between humans and mice can be accounted for in approximately six thousand genes (of ~30,000 total).
However, chimpanzees are rarely used in research and are protected from highly invasive procedures. The most common animal model is the rodent. Phylogenic trees estimate that humans and rodents last shared a common ancestor ~80-100mya. [5] [6] Despite this distant split, humans and rodents have far more similarities than they do differences ...
Comparative anatomy studies similarities and differences in organisms. The image shows homologous bones in the upper limb of various vertebrates. Comparative anatomy is the study of similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny [1] (the evolution of species).
The similarities between all present day organisms imply a common ancestor from which all known species, living and extinct, have diverged. More than 99 percent of all species that ever lived (over five billion) [1] are estimated to be extinct.
The annual life cycle has evolved in over 120 plant families across the entire angiosperm phylogeny. [213] Notably, the prevalence of annual species increases under hot-dry summer conditions in different families including Asteraceae, Brassicaceae, Fabaceae, and Poaceae. [212] Leaves have evolved multiple times - see Evolutionary history of plants.
The earliest fossils clearly in the human but not the chimpanzee lineage appear between about 4.5 to 4 million years ago, with Australopithecus anamensis. Few fossil specimens on the "chimpanzee-side" of the split have been found; the first fossil chimpanzee, dating between 545 and 284 kyr (thousand years, radiometric ), was discovered in Kenya ...