Table 1.

Participant demographics

	Total sample			Neuroimaging subset sample
	Altruists (N = 49)	Controls (N = 52)	p	Altruists (N = 23)	Controls (N = 25)	p
Gender (Male/Female, % Male)	15/34 (30.61%)	19/33 (36.54%)	.523	8/15 (34.78%)	10/15 (40.00%)	.709
Race (White/Non-White, % White)	44/5 (89.80%)	46/6 (88.46%)	.830	21/2 (91.30%)	23/2 (92.00%)	.931
Age, M (SD)	43.18 (10.63)	38.67 (8.68)	.021*	41.61 (9.75)	38.84 (8.03)	.287
Education ≥ Four-year degree	36/13 (73.47%)	47/5 (90.38%)	.026*	15/8 (65.21%)	18/7 (72.00%)	.123
Population (tens of thousands), M (SD)	2.54 (143)	2.79 (141)	.373	3.03 (145)	2.72 (139)	.434