Science - USA (2021-07-16)

(Antfer) #1
274 16 JULY 2021 • VOL 373 ISSUE 6552 sciencemag.org SCIENCE

PHOTO: ANUP SHAH/MINDEN PICTURES

By Josh A. Firth and Ben C. Sheldon

T

he social structure of a population
shapes many aspects of individuals’
lives. Network analysis details how
individuals are tied to one another
within a “social network” ( 1 ). Al-
though the relevance of social net-
works for behavior and ecology is becoming
well established, the processes that govern
their underlying structure, and individu-
als’ social positions relative to others, are
less well known ( 2 ). On p. 348 of this issue,
Ilany et al. ( 3 ) apply social network analy-
sis to a population of wild spotted hyenas
over 27 years and spanning multiple hyena
generations. Their findings support a pro-
posed model ( 2 ) that inheritance of social
network ties—specifically that offsprings’

social bonds are derived from their moth-
ers’ social affiliates—plays a key role in
shaping social structure across generations.
Furthermore, these inherited networks may
be linked to survival, providing a potential
selective force that promotes the evolution
of the inheritance of social networks.
Generally, the emergent properties of ani-
mal societies can be thought of as resulting
from individual-level variation in behavior
and individuals’ interactions with others ( 1 ).
Because these behaviors might have quite
simple bases, but nevertheless lead to com-
plex social network structures ( 4 ), it is rea-
sonable to suggest that social network prop-
erties of individuals might have heritable
components. Evidence from a range of or-
ganisms, from humans to fruit flies ( 5 ), sup-
ports this. However, what Ilany et al. demon-
strate is an altogether richer phenomenon.
Through combining detailed observations
with social network analysis, they demon-

strate that the specific social relationships of
hyenas resemble those of their mothers; that
this resemblance persists for many years,
even after parent-offspring social relation-
ships weaken; that offspring of higher-rank-
ing mothers and with closer bonds to their
mothers inherit their social networks to a
greater degree; and that this greater degree
of social network inheritance even predicts
increased survival of the offspring and of the
mother. Hence, rather than the social ten-
dencies of offspring resembling that of their
parents, it is the specific social networks that
are inherited (see the figure).
Ilany et al. provide new insights into the
generation of variation in social structure
and into how inheritance and sociality in-
teract, but their results also have wider
implications. The consequences of network
structure have been well demonstrated for
the interacting individuals within genera-
tions ( 1 ). However, if specific interactions

ANIMAL SOCIETIES

The long reach of family ties


PERSPECTIVES


In hyena societies, inherited social networks affect social behavior


INSIGHTS


Department of Zoology, University of Oxford, Oxford, UK.
Email: joshua.firth@zoo.ox.ac.uk; ben.sheldon@zoo.ox.ac.uk

Transgenerational legacy
in social interactions is observed
in spotted hyenas, which may
have consequences for the social
transmission of behaviors.

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