Crab-eating macaque 27% animal matter, 15% flowers and other plant matter, and 14% food provided by humans. This species exhibits particularly low tolerance for swallowing seeds. Despite their inability to digest seeds, many primates of similar size swallow large seeds, up to , and simply defecate them whole. The crab-eating macaque, though, spits seeds out if they are larger than . This decision to spit seeds is thought to be adaptive; it avoids filling the monkey’s stomach with wasteful bulky seeds that cannot be used for energy. It also can help the plants by distributing seeds to new areas: Crab-eating macaques eat
Crab-eating macaque and "M. f. condorensis" is vulnerable. All other subspecies are listed as data deficient and need further study; although recent work is showing "M. f. aurea" and "M. f. karimondjawae" need increased protection. One concern for conservation is, in areas where "M. fascicularis" is not native, their populations need to be monitored and managed to reduce their impact on native flora and fauna. The genome of the crab-eating macaque has been sequenced. On 24 January 2018, scientists in China reported in the journal "Cell" the creation of two crab-eating macaque clones, named "Zhong Zhong and Hua Hua", using the complex