Fossil history

The great white shark first unambiguously appears in the fossil record in the Pacific basin about 5.3 mya at the beginning of the Pliocene. Although there are few claims of fossils dated as early as 16 mya, their validity is doubted as mislabeled or misidentified. Like all sharks, the great white's skeleton is made primarily of soft cartilage that does not preserve well. The overwhelming majority of fossils as a result are teeth. Nevertheless, paleontologists have confidently traced the emergence of the great white shark and its immediate ancestry to a large extinct shark known as Carcharodon hastalis. This species appeared worldwide during the Early Miocene (~23 mya) and had teeth alike to the modern great white shark's, except that the cutting edges lacked serrations. The form was probably derived from an ancient lineage of large white sharks that arose in the early Eocene (~56-48 mya) from a primitive mako-like shark. C. hastalis occupied a middle to high trophic position in its ecosystems and was probably piscivorous (fish-eating) with some addition of marine mammals to its diet.

Around 8 mya, a Pacific stock of C. hastalis evolved into C. hubbelli. This divergent lineage, sometimes described as a chronospecies, was characterized by a gradual development of serrations over the next few million years. They were initially fine and sparse but a mosaic of fossils throughout the Pacific basin document an increase in quantity and coarseness over time, eventually becoming fully serrated as the great white shark's by 5.3 mya. Serrations are more effective at cutting prey than non-serrated edges, facilitating further specialization towards a mammal diet. It is likely the ancestral unserrated stock had already been regularly targeting marine mammals for millions of years, and therefore maintained an environment favoring rapid selection towards increasingly serrated teeth once a mutation for incipient serrations appeared. Teeth from the same strata may exhibit significant variation in serration development and morphology, which may be indicative of persistent interbreeding with C. hastalis for at least some time. The great white shark dispersed as soon as it emerged, with fossils in the Mediterranean, North Sea Basin, and South Africa occurring as early as 5.3–5 mya. Colonization of the northwestern Atlantic appeared to have delayed, with fossils absent until 3.3 mya.

Population genetics

Almost 60% of the white shark's genome consists of repeated sequences and comparisons with the genomes of other sharks and vertebrates suggests "the maintenance of genome stability in sharks". A 2020 mitochondrial DNA study concluded that Mediterranean sharks show closer affinity with Australia/New Zealand and North-eastern Pacific sharks than with sharks from South Africa and the north-western Atlantic. The researchers suggest that, over 3 mya, sharks from the former region swam to South Africa " became confused by Pleistocene climatic oscillations" and swam north where they ended up in the Mediterranean. A 2024 study states that "white shark mitogenomes are informative about the species’ deep history but are of very limited use for estimating recent connectivity". This autosomal (non-sexual nuclear DNA) study concluded that white shark populations can be divided into three major clades, North Atlantic (represented by the US East Coast and Mediterranean), Indo-Pacific (represented by Australia, New Zealand, and South Africa) and North Pacific (represented by California, Baja California, and East Asia) which diverged more recently around 100,000–200,000 in response to lowered sea levels. A 2025 study affirmed the existence of these three clades, but found that they diverged around 7,000 years ago following a decline in the global white shark population which started 800,000 years ago.