Wednesday, May 2, 2012

Ape nests

[not included: morotopith hanging orthogrady, raptorial mimicry, human dome hut derivation]

Nest-building orangutans demonstrate engineering know-how to produce safe,

comfortable beds

Adam van Casteren cs 2012 PNAS

Orangutans must daily build safe & comfortable nest structures in the

forest canopy,

they do this quickly & effectively, using the branches that surround them.


We measured the whole nest compliance & the thickness of the branches

used, and recorded the ways in which the branches were fractured.

Branch samples were also collected from the nests, and subjected to

3-point bending tests to determine their mechanical properties.

We demonstrated

- The center of the nest is more compliant than the edges. This may add

extra comfort & safety to the structure.

- During construction, orangs use the fact that branches only break

half-way across in "green-stick" fracture to weave the main nest

structure. They choose thicker branches with greater rigidity & strength

to build the main structure in this way.

- They then detach thinner branches by following greenstick fracture with

a twisting action to make the lining.

These results suggest that orangutans exhibit a degree of technical

knowledge & choice in the construction of nests.

No comments: