In a study of wild primates, reported this week (Nov. 7, 2011) in the Proceedings of the National Academy of Sciences, University of Wisconsin-Madison anthropologist Karen B. Strier describes a monkey society where equality and tolerance rule and where sexually mature males, still living at home, seem to get helpful access to mates by the mere presence of their mothers and other maternal kin.
The new study, which combines Strier’s long-term behavioral studies of wild muriquis with new genetic assays obtained from their scat, is important because it can inform conservation practices for critically endangered primates. But the study's big surprise, says Strier, was evidence that could extend the 'grandmother hypothesis,' the notion that human females evolved to live well past their reproductive years because of the rearing advantages conferred by post-menopausal women on their grandchildren.
The northern muriqui is a large, long-lived, socially complex and critically endangered New World primate. There are at most 1,000 animals left in patches of the Brazilian Atlantic Forest , the only place the species is found.
The monkey has been the subject of intensive behavioral study by Strier and her Brazilian colleagues for nearly three decades. Muriqui culture stands in stark contrast to many other primate societies: It is egalitarian, peaceful, and reproductive success, it seems, is spread evenly across the males of a group instead of determined by male social rank, as it is in most other species.
“The new data show who’s pulling the strings in muriqui society,” says Strier. “It’s the mothers.”
Genetic data from 67 monkeys – infants, mothers and possible sires – was gathered from monkey feces and analyzed with collaborators Sérgio Mendes and Valéria Fagundes of the Universidade Federal do Espirito Santo, Brazil, Anthony Di Fiore of the University of Texas at Austin, and Brazilian graduate student, Paulo Chaves at New York University. The genetic results, says Strier, neatly validate decades of behavioral studies, and provide a new window into muriqui society as Strier and her group could see, for the first time, paternal relatives across generations in highly stable social groups.
“We knew from long-term behavioral studies that mothers, who can live into their thirties, stay with their sons for a lifetime,” explains the Wisconsin anthropologist, “but the unexpected part of the story is that there may be reproductive advantages as a result of this living arrangement”.
“It would be really interesting now to look at paternity in other muriqui populations and in other species where mothers and sons stay together for life, to see if there are similar maternal effects,” says Strier.
The new research may also help explain why muriqui monkey females are so long lived.
The genetic data used in the study reveal that paternity in the group is more evenly spread across potential fathers, with 22 infants sired by 13 different males. The most successful male fathered just 18 percent of infants, a far lower percentage than reported for other primate species living in multi-male groups.
According to Strier, it can be difficult to tell from behavioral observations who’s a father and who isn’t, as muriqui males often line up patiently to mate with ovulating females.
“What we see is that no one male is monopolizing reproduction,” explains Strier. “The pattern is that a lot of different males are siring infants, confirming what we had predicted from their behavior.”
Strier’s studies have shown that in muriqui society, males stay in the groups they were born in while most females migrate to other groups at 6 or 7 years of age.
Intriguingly, no infants were the result of mating between males and a close maternal relative. “The finding that no inbreeding is occurring is important,” Strier avers. “Mating may be less random than we think because of the influence of mothers and other maternal kin. There must be some mechanism of recognition or avoidance.”
This is a crucial discovery, given that the 300 or so muriquis in Strier’s study population (representing nearly one-third of the entire species) are found in a protected reserve, where they are isolated from other muriquis.
The new PNAS report and supporting data open a vital new perspective on primate social dynamics. “Are we seeing mega moms? Or is this really just about being with your mom?"
The new study, says Strier, will also help with muriqui conservation, as what little muriqui habitat remains is fragmented. The data suggest that this muriqui population may be large enough for its members to avoid close inbreeding, so protection aimed at preserving and expanding habitat for existing groups would suffice.
At the same time, the influence of mothers and other maternal kin on male reproduction suggest the importance of extended families in this species. If animals living in smaller populations ever need to be relocated for conservation purposes, they should be moved with great care, Strier notes.
Karen Strier (608) 262-0302, email@example.com
Terry Devitt | Newswise Science News
Solving the efficiency of Gram-negative bacteria
22.03.2019 | Harvard University
Bacteria bide their time when antibiotics attack
22.03.2019 | Rice University
DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.
The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...
Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.
The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
22.03.2019 | Life Sciences
22.03.2019 | Life Sciences
22.03.2019 | Information Technology