Daily Archives: January 9, 2015

Study: Ancient humans developed weaker bones as they hunted less

By Daniel Xu

The OutdoorHub

For much of human history, our ancestors lived in nomadic, hunter-gatherer societies. It was only a few thousand years ago that humans began moving toward agriculture as a way of life, which drastically changed not only food production, but human civilization as a whole. Scientists now say that the invention of farming may have had a physical effect on early humans as well. A recent study conducted in the journal Proceedings of the National Academy of Sciences (PNAS) found that human hunter-gatherers from around 7,000 years ago had much stronger bones compared to their farming descendants 1,000 years later. According to the study, the bone mass of hunter-gatherer humans was about 20 percent higher than that of the farmers. This loss in bone density is attributed to the increasingly sedentary lifestyle provided by efficient agricultural practices, as opposed to strenuous activity of hunting and foraging.

“Sitting in a car or in front of a desk is not what we have evolved to do,” said study co-author Colin Shaw of CambridgeUniversity in a press release.

An earlier study by researchers at the Smithsonian National Museum of Natural History found that the change in bone density first occurred about 12,000 years ago, when humans started to explore farming. The bone strength of the hunter-gatherer humans was similar to that of a modern orangutan, whereas farmers from the same area many years later would have lighter and weaker bones more susceptible to breaking. Discovery Magazine reported that both studies were interested in changes to trabecular bone, the spongy honeycomb-like structure inside our bones. Trabecular bone provides bone with added strength and durability, but can also adjust to increased stress. This is why regular exercise can increase the strength of your bones.

“It can change structure from being pin or rod-like to much thicker, almost plate-like. In the hunter-gatherer bones, everything was thickened,” said Shaw. “The fact is, we’re human, we can be as strong as an orangutan—we’re just not, because we are not challenging our bones with enough loading, predisposing us to have weaker bones so that, as we age, situations arise where bones are breaking when, previously, they would not have.”

0          There are other theories regarding why humans have developed a weaker, more fragile skeleton. Some scientists say that the change in diet may have caused the decrease in bone mass, or that humans simply adapted to their new role with a lighter, more agile frame. One thing that did surprise researchers is how rapid the change was, and how recently it took place.

“This was absolutely surprising to us,” Habiba Chirchir, a co-author on the second study also published in PNAS, told NPR. “The change is occurring much later in our history.”

PASSENGER PIGEON RESOLUTION PASSES SENATE

Just before wrapping up business last month on 16 December, the U.S. Senate passed a resolution by unanimous consent, calling attention to the 100th anniversary of the extinction of the last known Passenger Pigeon. The resolution was pioneered by Ohio’s two Senators, Sherrod Brown (D) and Rob Portman (R). Ohio, not coincidentally was where the last known Passenger Pigeon, “Martha,” died  – at the Cincinnati Zoo in 1914.

“The extinction of plants and animals from our planet should serve as a wakeup call,” Senator Brown said.

Senator Portman added, “The loss of this species is one of the greatest examples of what can happen if we are not committed to conserving our wildlife. We must learn from their example, and I am proud that this Resolution brings light to this important issue.”

The reasoning for the resolution and its exact wording can be found on this original release:

http://www.brown.senate.gov/newsroom/press/release/brown-portman-introduce-senate-resolution-on-the-100th-anniversary-of-the-extinction-of-the-passenger-pigeon

 

Genomic Sequencing Breakthrough Maps the Avian Family Tree

Last month, a remarkable consortium of more than 200 scientists from 20 countries released the results of an enormous cooperative research endeavor – the mapping of an expansive avian family tree that demonstrates how birds evolved their amazingly colorful feathers, lost their teeth, learned to sing, and how their brain circuitry functions.

Members of the project, named the Avian Phylogenomics Consortium, published their family-tree findings in eight different papers in the journal Science, and also in more than 20 other scientific journals. No one had ever before used so much genome data from so many species to determine evolutionary relationships.

This project has re-arranged what we know about birds and has revealed unexpectedly close family relationships. For example the study clearly established that falcons are more closely related to parrots than to eagles or vultures (neither Old World nor New World vultures), and that flamingoes are actually evolutionarily and genetically closer to pigeons than they are to pelicans!

“It’s mind-blowing,” said Per Ericson, an evolutionary biologist at the SwedishMuseum of Natural History in Stockholm.

According to an article by Ian Sample in The Guardian, an analysis of the genomes indicated that the common ancestor of living birds lost its teeth more than 100 million years ago. But the significant rise of the birds began about 65 million years ago. A mass extinction – probably caused by an asteroid collision – extinguished most of the larger-bodied dinosaurs, but left a few feathered creatures. The loss of so many other species freed up significant ecological niches, giving these feathered animals a unique chance to diversify.

You can find more on this genome story here:

http://www.theguardian.com/science/2014/dec/11/birds-evolution-feathers-genome-sequencing-avian-genes  and here:

http://www.nature.com/news/flock-of-geneticists-redraws-bird-family-tree-1.16536