Yes, a human can have seven fingers. This condition, known as polydactyly, is a relatively rare congenital anomaly where a person is born with extra fingers or toes. While the typical number of fingers is five, genetic variations or mutations during development can lead to the presence of extra digits. The severity and the number of extra digits can vary widely.
One example, cited from a news source, describes a person with "seven fingers in each hand and six toes in each leg" This demonstrates that having more than the usual number of digits is possible, even if uncommon. [Source: “The girl has seven fingers in each hand and six toes in each leg. The condition is called Polydactyly, which is rare but there is no harm or side effect of this condition on the body,” Soni said.18-Sept-2023]
Several online discussions also corroborate the existence of individuals with seven fingers:
- Reddit threads on evolution and AskScience discuss the possibility of having more than five fingers, pointing out that while five is the most common number, variations occur. [Sources: https://www.reddit.com/r/askscience/comments/1bm20w0/why_five_fingers_why_not_3_7_or_9/, https://www.reddit.com/r/evolution/comments/1bq35us/did_humansan_ancestor_of_humans_have_more_than_5/]
- Quora answers confirm the existence of polydactyly and explain that it's due to genetic factors. [Sources: https://www.quora.com/Do-people-with-six-or-seven-fingers-on-one-hand-exist-If-so-how-do-they-react-upon-realizing-this-difference-between-them-and-others-people-around-them, https://www.quora.com/Are-there-humans-with-seven-fingers-on-each-hand]
While the precise prevalence of polydactyly isn't definitively stated in the provided resources, it's clear from the available information that individuals with seven fingers do exist. The medical term for having extra fingers or toes is polydactyly.
