This week has once again been a rich one for learning more about the fascinating lives of other animals, our own brains and how they differ from those of other animals, and the importance of spending time outside.
Pachyderm politics and the powerful female
An up-to-date summary of the behavior and importance of female matriarch elephants has recently been published in New Scientist magazine in an essay called "Pachyderm politics and the powerful female." Because as of now this article is only available to subscribers to New Scientist, here I summarize some of the major points of this outstanding essay by Lesley Evans Ogden.
Female elephants rule. As Ms. Ogden notes, "It has long been clear that elephant groups rely on their elder stateswomen, but just how important these females are is only gradually becoming apparent. Matriarchs are at the hub of a complex, multilayered social network, and we are now getting insights into the nature of the ties that bind these close-knit groups and the key role that wise old leaders play in enhancing the survival of their members. Matriarchs carry with them a treasure trove of crucial information. They have a unique influence over group decision-making. And, like our own leaders, the most successful may even possess certain personality traits."
Much of what she writes stems from more than four decades of detailed research on a relatively undisturbed population of elephants living in the Amboseli National Park in southern Kenya. To quote renowned scientist Cynthia Moss, who founded the Amboseli Elephant Research Project (AERP) in 1972 and continues to lead the research, "Our studies show how absolutely crucial matriarchs are to the well-being and success of the family."
The elephants in Amboseli exhibit a complex fluid fission-fusion society that is rarely observed in animals other than humans or non-human primates. And, the oldest and most experienced females take the lead. Ms. Ogden notes, "But group size is constantly changing, responding to the seasons, the availability of food and water, and the threat from predators. An adult female elephant might start the day feeding with 12 to 15 individuals, be part of a group of 25 by mid-morning, and 100 at midday, then go back to a family of 12 in the afternoon, and finally settle for the night with just her dependent offspring." And, other research has shown that "the more closely related individuals are, the more time they tend to spend with one another (Proceedings of the Royal Society, B, vol 273, p 513)."
Furthermore, there appears to be a survival advantage for groups led by older matriarchs. Vicki Fishlock, a resident scientist with the AERP notes, "Good matriarch decisions balance the needs of the group, avoiding unnecessary travel while remembering when and where good resources are available. ... The matriarch has a very strong influence on what everybody does." Indeed, "Studies in Amboseli have revealed that families with older, larger matriarchs range over larger areas during droughts, apparently because these females better remember the location of rare food and water resources." A number of different studies have shown that groups benefit from the presence of "wise old matriarchs" and that "elephants defer to the knowledge of their elders, and that matriarchs call the shots when it comes to deciding what anti-predator strategy to adopt" according to elephant expert Karen McComb at the UK's University of Sussex.
A few more significant discoveries include:
"Older matriarchs also seem to be better at judging "stranger danger" from other elephants. At Amboseli, each family group encounters some 25 other families in the course of the year, representing about 175 other adult females. Encounters with less familiar groups can be antagonistic and if a family anticipates possible harassment it assumes a defensive formation called bunching. McComb tested whether a matriarch's age influenced her ability to discriminate between contact calls. In a playback experiment, her team found that families led by older matriarchs were less reactive overall, but bunched more in response to the sound of less familiar individuals than did families led by younger females. They suspect this is because older matriarchs have a larger memory catalogue for elephant voices, allowing them to more precisely distinguish between familiar and unfamiliar ones, and respond appropriately."
Cynthia Moss and her colleagues have identified 26 different personality types among elephants "which group into four main personality dimensions: playfulness, gentleness, constancy and leadership. So far they have analysed just 11 adult females from one Amboseli family, and the matriarch does score highly in the leadership dimension."
And, Ogden concludes, "We do not yet know the full extent of the damage caused by the killing of wise old matriarchs. Given that they are instrumental in solving the everyday problems of keeping their groups fed, watered, safe and reproducing, their entire social network will feel the loss. But work by [Colorado State University's George] Wittemyer and [Iain] Douglas-Hamilton [founder of Save the Elephants] on heavily poached elephant populations suggests that despite disruptions to social structure, over the long term, the elephants and their networks are resilient. They can and will recover if poaching pressure can be lifted, but that is a big 'if'."
"Matriarchs may be adept at solving the problems faced by the elephants that look to them for leadership, but at the moment humans are their greatest problem, one that they cannot resolve for themselves."
I hope this wonderful essay becomes available sooner rather than later.
Untethered brains: Size isn't everything
An essay in the New York Times by Carl ZImmer called "In the Human Brain, Size Really Isn’t Everything" also caught my attention. Human brains are larger, relative to body size, than are the brains of other animals (for more discussion please see "The Birds and the Bees and Their Brains: Size Doesn't Matter.") Because absolute brain size can be a misleading measure researchers often rely on the encephalization quotient (EQ) when making comparisons of brain size among different species. The EQ is "a measure of relative brain size defined as the ratio between actual brain mass and predicted brain mass for an animal of a given size'. Estimates for the EQ's for different species and discussions of what they mean about intelligence and various behavior patterns can be seen here and here.
Mr. Zimmer writes about research by Harvard neuroscientists Randy Buckner and Fenna Krienen that supports the argument that size isn't everything. He writes, "In our smaller-brained ancestors, the researchers argue, neurons were tightly tethered in a relatively simple pattern of connections. When our ancestors’ brains expanded, those tethers ripped apart, enabling our neurons to form new circuits". This is called the tether hypothesis and you can read more about it in an essay called "The evolution of distributed association networks in the human brain" published in Trends in Cognitive Sciences.
In a nutshell, human brains, when compared with the brains of other animals, have large association cortices. And, "Association cortices are also unusual for their wiring. They are not connected in the relatively simple, bucket-brigade pattern found in other mammal brains. Instead, they link to one another with wild abandon. A map of association cortices looks less like an assembly line and more like the Internet, with each region linked to others near and far. ... Our association cortices liberate us from the rapid responses of other mammal brains. These new brain regions can communicate without any input from the outside world, discovering new insights about our environment and ourselves."
All this isn't to say that human brains are "better" than nonhuman brains. Animals do what they need to do to be card-carrying members of their species and clearly the demands of "being human" necessitated the evolution of brains that are structurally and functionally different from those of other animals. I find the tether hypothesis to be a fascinating idea.
Getting outside is good for our mental health
The last essay I found to be very interesting is called "DO PARKS BOOST LONG-TERM MENTAL HEALTH?" and the answer is a resounding "yes". Based on the results of their study published in Environmental Science & Technology called "Longitudinal Effects on Mental Health of Moving to Greener and Less Green Urban Areas," the authors conclude that living around greener areas has positive effects on mental health that are sustainable over time and "that environmental policies to increase urban green space may have sustainable public health benefits."
So, getting out is good and does not simply have immediate positive effects. More research is needed but this is a very exciting and important discovery.
Stay tuned for more on the fascinating lives of other animals and why getting out is good for one's mental health (see also essays by Psychology Today writer and conservation psychologist Susan Clayton).