ATR 250
Chapter 6: Biology in the Present: The Other Living Primates

Altruistic- Refers to a behavior that benefits others while being a disadvantage to the individual
   Arboreal adaptation- A suite of physical traits that enable an organism to live in trees.
Bilophodont- Refers to lower molars, in Old World monkeys, that have two ridges.
Brachiators-Organisms that move by brachiation, or arm-swinging.
Canine-premolar honing complex- The dental form in which the upper canines are sharpened against the 
lower third premolars when the jaws are closed
dental formula- The numerical description of a species' teeth, listing the number, in one quadrant of the 
jaws, of incisors, canines, premolars, and molars
diastema- A space between two teeth
dietary plasticity- A diet's flexibility in adapting to a given environment
diurnal- Refers to those organisms that normally are awake and active during daylight hours
habituate- Refers to the process of animals becoming accustomed to human observers
hominin- Humans and human ancestors in a more recent evolutionary taxonomy; based on genetics
infanticide- The killing of a juvenile
kin selection- Altruistic behaviors that increase the donor's inclusive fitness, that is, the fitness of the 
donor's relatives
loph- An enamel ridge connecting cusps on a tooth's surface
monogamous- Refers to a social group that includes an adult male, an adult female, and their 
offspring
olfactory bulb- The portion of the anterior brain that detects odors
opposable- Refers to primates' thumb, in that it can touch each of the four fingertips, enabling a 
grasping ability
parental investment- The time and energy parents expend for their offspring's benefit
polyandrous- Refers to a social group that includes one reproductively active female, several adult 
males, and their offspring 
polygynous- Refers to a social group that includes one adult male, several adult females, and their 
offspring
power grip- A fistlike grip in which the fingers and thumbs wrap around an object in opposite directions
preadaptation- An organism's use of an anatomical feature in a way
precision grip- A precise grip in which the tips of the fingers and thumbs
prehensile tail- A tail that acts as a kind of a hand for support in trees,
primatologists- Researchers that study nonhuman primates
rhinarium- The  naked  surface  around  the  nostrils,  typically wet in mammals
sectorial (premolar)- Refers to a premolar adapted for cutting
sexual selection- The frequency of traits that change due to those traits' attractiveness to members of the 
opposite sex
tooth comb- Anterior teeth that have been tilted forward, creating a scraper
Y-5- Hominoids' pattern of lower molar cusps