Tag Archives: enlarged

Discovering the origins of your brain’s enlarged size

Posted on by
Reply

Recent research has uncovered the reason behind the evolution of our brains, pointing to the influence of gut microbes. Specifically, the study suggests that the intestines may have played a key role in boosting energy production over time, leading to the growth of crucial organs.

The study reveals that organisms with larger brains relative to body size, like humans and squirrel monkeys, have higher energy levels compared to those with smaller brains, thanks to their digestive microbes. These microbes help in breaking down food and producing energy efficiently.

This groundbreaking research is the first to demonstrate how the gut microbiome can drive biological differences between animal species.

“The connection between the gut and brain has always been acknowledged on some level. We often refer to ‘gut feelings,’ and it’s known that stress and anxiety can manifest as gut symptoms,” said lead author of the study, Katherine Amato, Associate Professor at Northwestern University, in an interview with BBC Science Focus.

Amato further elaborated, stating, “This study goes beyond that and proposes that the activities in the gut may have laid the groundwork for the evolution of our brains.”

The intestines harbor over 100 trillion microorganisms, a count that surpasses the number of cells in the body. These intestinal microbes collectively weigh around 2 kg (4.4 pounds) – equivalent to the weight of a large pineapple.

Researchers were particularly intrigued by how these tiny gut microbes influence brain size in relation to body size. While humans may not have the largest brains in the animal kingdom, they have a significantly higher brain-to-body ratio compared to other species.

The experiment, detailed in the journal microbial genomics, involved transferring gut microbes from three primate species to mice – two with large brains (humans and squirrel monkeys) and one with a small brain (macaque). The results showed that mice receiving gut bacteria from larger-brained species produced more energy to support brain function, while those with gut flora from smaller-brained primates stored more energy as fat.

Amato explained, “Our findings suggest that as humans and squirrel monkeys independently evolved larger brains, their microbial communities also adapted in similar ways to meet the energy demands.” The study also found that the outcomes of feeding human microbes to mice were more akin to other large-brained species than previously thought.

Researchers are now extending their studies to other primate species to further explore the impact of gut microbes on brain evolution.

About our experts:

Dr. Katherine Amato is an Associate Professor of Biological Anthropology at Northwestern University in Illinois, USA. Her research interests include the gut microbiome, human evolution, and primate ecology.

Read more:

Source: www.sciencefocus.com

Male lemurs exhibit enlarged testicles in the presence of other males

Posted on by
Reply

Male Verreaux’s Sifaka

Gabriel Bueno

Dominant male lemurs grow more flexible testicles when other males are present, improving their position for successful mating.

In many species, dominant males have larger testes than subordinate males. Increased Testosterone Research has also shown that males of group-living, multi-male species have larger testes than males of group-living, single-male species. Larger testes mean more sperm can be produced, which increases the male’s chances of producing offspring if a female mates with multiple males.

Gabriel Bueno and Rebecca Lewis Researchers at the University of Texas at Austin tested whether this pattern held true within a single population by looking at testicle size in 23-year-old adult men. Verreaux’s sifaka (Propithecus beleaucii) took place outside of the mating season over a 13-year period in Kirindimitea National Park in western Madagascar.

This lemur group is made up of several groups, some with only one male and some with several. As in all lemur societies, the females hold the most social power, but the males also have their own hierarchy. Dominant lemurs have greasy brown spots on their chests from constant scent marking, while subordinate lemurs have clean white bodies.

The researchers found that the testicles of stained males in multi-male groups were on average 103 percent larger than those of clean males from the same groups and 31 percent larger than those of stained males in single-male groups. The stained lemurs in multi-male groups may be producing more testosterone than other lemurs or they may be suppressing the amount of testosterone that clean males can produce, Bueno says.

Stained males living in multi-male groups not only have larger scrotums in absolute terms, but also larger relative to their body size, which Bueno says suggests indicates that dominant males spend more energy competing for sperm when there are other males around.

“The key is that they can make that switch,” Bueno says. Because the dominant male always has the largest testicles, when a dirty male with larger testicles enters the group, the dirty male’s gonads grow. This “highlights how extraordinarily flexible they are and how they adapt to their social environment,” Bueno says.

“It is surprising that males can flexibly adjust their testis size across a range of environments throughout their lives,” he said. Peter Kappeler The researchers, from the University of Göttingen in Germany, added that their findings raise important questions about the potential costs of maintaining large testes: Enlarging them requires energy that cannot be used elsewhere, and likely requires the animal to search for more food.

topic:

Source: www.newscientist.com