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Laziness genes possibly found

April 10, 2013
Courtesy of the University of Missouri
and World Science staff

Sci­en­tists have added a new twist to the ar­gu­ment over wheth­er obes­ity stems from la­zi­ness and poor self-con­trol—or an un­for­tu­nate mix of genes.

The mon­key wrench now thrown in­to the de­bate is this: la­zi­ness it­self may be partly ge­net­ic.

While it might not be a good idea to try us­ing that to ex­plain your­self your boss, “we have shown that it is pos­si­ble to be ge­net­ic­ally pre­dis­posed to be­ing lazy,” said Frank Booth of the Uni­vers­ity of Mis­souri Col­lege of Vet­er­i­nary Med­i­cine.

Booth and re­search col­league Mi­chael Roberts bred sep­a­rate groups of rats for both re­mark­a­ble ac­tive­ness and stu­pe­fy­ing la­zi­ness. As a re­sult, “we iden­ti­fied 36 genes that may play a role in pre­dis­po­si­tion to phys­i­cal ac­ti­vity mo­tiva­t­ion,” ex­plained Roberts.

“This could be an im­por­tant step in iden­ti­fy­ing ad­di­tion­al causes for obes­ity in hu­mans, es­pe­cially con­sid­er­ing dra­mat­ic in­creases in child­hood obes­ity in the Un­ited States,” said Booth. Hu­mans have been found to share about four-fifths of their genes with mice and rats. “It would be very use­ful to know if a per­son is ge­net­ic­ally pre­dis­posed to hav­ing a lack of mo­tiva­t­ion to ex­er­cise, be­cause that could po­ten­tially make them more likely to grow obese.”

Stud­ies show just three per­cent of Amer­i­can adults ex­er­cise the min­i­mum rec­om­mended amount based on fed­er­al guide­lines, half an hour a day. 

Booth and Roberts put rats in cages with run­ning wheels and meas­ured how much each rat will­ingly ran on the wheels over six days. They then bred the top 26 run­ners with each oth­er and bred the 26 rats that ran the least with each oth­er. They re­peat­ed that through 10 genera­t­ions and then found that the “active” rats chose to run 10 times more than the “lazy” rats.

The study was pub­lished April 3 in the Amer­i­can Jour­nal of Phys­i­ol­o­gy: Reg­u­la­tory, In­te­gra­tive and Com­par­a­tive Phys­i­ol­o­gy.

Hav­ing cre­at­ed their “su­per run­ner” and “couch pota­to” ro­dents, the re­search­ers stud­ied the lev­els of mi­to­chon­dria in mus­cle cells. Mi­to­chon­dria are or­ganelles, or small com­part­ments, that have been de­scribed as the pow­er plants of cells. The in­ves­ti­ga­tors al­so com­pared body com­po­si­tion and con­ducted thor­ough ge­net­ic evalua­t­ions.

“While we found mi­nor dif­fer­ences in the body com­po­si­tion and lev­els of mi­to­chon­dria… the most im­por­tant thing we iden­ti­fied were the ge­net­ic dif­fer­ences,” Roberts said. The 36 genes iden­ti­fied—which the re­search­ers plan to study for their in­di­vid­ual ef­fects on mo­tiva­t­ion—were “out of more than 17,000 dif­fer­ent genes [act­ing] in one part of the brain.”


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Scientists have just added a new twist to the old argument over whether obesity results from simple laziness, or an unfortunate mix of genes. The monkey wrench now thrown into the debate is this: laziness itself may be genetic. While it might not be a good idea to try using that to explain yourself your boss, “we have shown that it is possible to be genetically predisposed to being lazy,” said Frank Booth of the University of Missouri College of Veterinary Medicine. Booth and research colleague Michael Roberts bred separate groups of rats for both remarkable activeness and stupefying laziness. As a result, “we identified 36 genes that may play a role in predisposition to physical activity motivation,” explained Roberts. “This could be an important step in identifying additional causes for obesity in humans, especially considering dramatic increases in childhood obesity in the United States,” said Booth. Humans have been found to share about four-fifths of their genes with mice and rats. “It would be very useful to know if a person is genetically predisposed to having a lack of motivation to exercise, because that could potentially make them more likely to grow obese.” Studies show just three percent of American adults exercise the minimum recommended amount based on federal guidelines, half an hour a day. Booth and Roberts put rats in cages with running wheels and measured how much each rat willingly ran on the wheels over six days. They then bred the top 26 runners with each other and bred the 26 rats that ran the least with each other. They repeated that through 10 generations and found that the line of running rats chose to run 10 times more than the line of “lazy” rats. The study was published April 3 in the American Journal of Physiology: Regulatory, Integrative and Comparative Physiology. Having created their “super runner” and “couch potato” rodents, the researchers studied the levels of mitochondria in muscle cells. Mitochondria are organelles, or small compartments, that have been described as the power plants of cells. The investigators also compared body composition and conducted thorough genetic evaluations. “While we found minor differences in the body composition and levels of mitochondria… the most important thing we identified were the genetic differences,” Roberts said. The 36 genes identified—which the researchers plan to study for their individual effects on motivation—were “out of more than 17,000 different genes in one part of the brain.”