Table 2.

Comparative life-history variables and age at M1 emergence in extant great apes and humans

Variable	Gorilla	Pan	Pongo	Homo
Age at first reproduction, y	10.1* (51.3%)	14.3† (72.6%)	15.7‡ (79.7%)	19.7
Interbirth interval, y	4.3	5.8†	6.9‡	3.4§
Survivorship, y||	?	29.7 (54.9%)	43.0 (79.5%)	54.1
Age at M1 emergence, y	3.8 (65.5%)	4.0† (69.0%)	4.6‡ (79.3%)	5.8

Numbers in parentheses indicate the percentage relative to values in humans. Life history sources: Gorilla (23, 24); Pan (25); Pongo (26); Homo (27); all survivorship data from ref 27. M1 sources: Pan (4); Homo (21, 22); Gorilla and Pongo (present study).

*Value for mountain gorilla, G. g. beringei, which is likely to be earlier than in G. g. gorilla (see text for explanation).

^†Values for P. t. verus only (Taï Forest, Ivory Coast).

^‡Values for P. p. pygmaeus only (Borneo), omitting a single value for age at first reproduction from Gunung Palung (26), which involves an age estimate.

^§Interbirth interval is anomalously low in modern humans compared with other anthropoid species. This life-history variable is included for between-ape comparisons only and percentages of human values were not calculated.

^||Expected age at death at age 15 y based on empirically derived survival curves (see Materials and Methods for further discussion).