为什么人类在四万年前已经能够远航和用火了，但是最早的文明记录却是 5000 年前的，这三万多年人类在干嘛？

human race

(of sb or sth) to be (located) at

(used after a noun, verb or adjective to form a nominal expression, as in 皮革的[pi2 ge2 de5] "one made of leather" or 跑堂兒的|跑堂儿的[pao3 tang2 r5 de5] "a waiter (literally, one who runs back and forth in a restaurant)" or 新的[xin1 de5] "new one")

why?

already

usefulness; utility

culture

(bound form) this; the (followed by a noun)

four

to understand clearly

fire

but; however

CL:個|个[ge4]

variant of 年[nian2]