Navigation Links
Seeing the serpent

The ability to spot venomous snakes may have played a major role in the evolution of monkeys, apes and humans, according to a new hypothesis by Lynne Isbell, professor of anthropology at UC Davis. The work is published in the July issue of the Journal of Human Evolution.

Primates have good vision, enlarged brains, and grasping hands and feet, and use their vision to guide reaching and grasping. Scientists have thought that these characteristics evolved together as early primates used their hands and eyes to grab insects and other small prey, or to handle and examine fruit and other foods.

Isbell suggests instead that primates developed good close-up eyesight to avoid a dangerous predator -- the snake.

"A snake is the only predator you really need to see close up. If it's a long way away it's not dangerous," Isbell said.

Neurological studies by others show that the structure of the brain's visual system does not actually fit with the idea that vision evolved along with reaching and grasping, Isbell said. But the visual system does seem to be well connected to the "fear module," brain structures involved in vigilance, fear and learning.

Fossils and DNA evidence show that snakes were likely the first serious predators of modern mammals, which evolved about 100 million years ago. Fossils of snakes with mouths big enough to eat those mammals appear at about the same time. Other animals that could have eaten our ancestors, such as big cats, and hawks and eagles, evolved much later.

Venomous snakes evolved about 60 million years ago, raising the stakes and forcing primates to get better at detecting them.

"There's an evolutionary arms race between the predators and prey. Primates get better at spotting and avoiding snakes, so the snakes get better at concealment, or more venomous, and the primates respond," Isbell said.

Some primate groups less threatened by snakes show fewer signs of evolutionary press ure to evolve better vision. For example, the lemurs of Madagascar do not have any venomous snakes in their environment, and in evolutionary terms "have stayed where they are," Isbell said. In South America, monkeys arrived millions of years before venomous snakes, and show less specialization in their visual system compared with Old World monkeys and apes, which all have good vision, including color.

Having evolved for one purpose, a good eye for color, detail and movement later became useful for other purposes, such as social interactions in groups.

Isbell is currently working on a book about primate origins, including her snake hypothesis.


'"/>

Source:University of California - Davis


Related biology news :

1. Seeing the forest and the trees
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:8/15/2017)... --  ivWatch LLC , a medical device company focused on improving ... of its ISO 13485 Certification, the global standard for medical device ... (ISO®). ... Monitoring device for the early detection of IV infiltrations. ... "This is an important milestone for ivWatch, as it ...
(Date:5/23/2017)... 23, 2017  Hunova, the first robotic gym for the rehabilitation and ... launched in Genoa, Italy . The first 30 robots ... the USA . The technology was developed and patented ... the IIT spin-off Movendo Technology thanks to a 10 million euro investment ... please click: ...
(Date:4/19/2017)... 2017 The global military biometrics ... marked by the presence of several large global players. ... five major players - 3M Cogent, NEC Corporation, M2SYS ... nearly 61% of the global military biometric market in ... global military biometrics market boast global presence, which has ...
Breaking Biology News(10 mins):
(Date:10/12/2017)... ... 12, 2017 , ... The Blavatnik Family Foundation and the ... of the 2017 Blavatnik Regional Awards for Young Scientists. Established in 2007, ... the New York Academy of Sciences to honor the excellence of outstanding postdoctoral ...
(Date:10/12/2017)... ... October 12, 2017 , ... ... Market with the addition of its newest module, US Hemostats & Sealants. , ... thrombin hemostats, absorbable hemostats, fibrin sealants, synthetic sealants and biologic sealants used in ...
(Date:10/11/2017)... N.C. (PRWEB) , ... October 11, 2017 , ... ... ARCS® Foundation President Andi Purple announced Dr. Suneel I. Sheikh, the co-founder, ... ( ASTER Labs ), Inc. has been selected for membership in ARCS ...
(Date:10/11/2017)... ... 11, 2017 , ... ComplianceOnline’s Medical Device Summit is back for its 4th ... in San Francisco, CA. The Summit brings together current and former FDA office bearers, ... and government officials from around the world to address key issues in device compliance, ...
Breaking Biology Technology: