Chin

The chin or the mental region is the area of the face below the lower lip and including the mandibular prominence. It tends to be smaller and more rounded in human females, while bigger and more square in human males. It is formed by the lower front of the mandible. In humans there is a wide variety of chin structures, e.g. cleft chin.

In human evolution, the chin is a cladistic apomorphy, partially defining anatomically modern humans as distinct from archaic forms. Non-human anthropoid apes have a simian shelf for example. Elephants are the only other animals considered to display such a feature, although this leads to debate over the use of the term.

The chin emerged during the Middle and Late Pleistocene, but its origin and biomechanical significance are the subjects of controversy. Prominent hypotheses include buttressing the jaw against stresses resulting from speech or chewing as well as simple sexual selection through mate choice. With the advent of more advanced computational facilities, finite element analyses have been used to support hypotheses involving mechanical stress. On the other hand, increased availability of data regarding sexual dimorphism in chins has also lent support to the sexual selection hypothesis as sexual dimorphism is more difficult to explain under other regimes. It is possible that multiple causal factors have played a role in the chin's evolution.

Log cabin

A log cabin is a dwelling constructed of logs, especially a less finished or architecturally sophisticated structure. Log cabins have an ancient history in Europe, and in America are often associated with first generation home building by settlers.

European history of log cabins

Construction with logs was described by Roman architect Vitruvius Pollio in his architectural treatise De Architectura. He noted that in Pontus (modern-day northeastern Turkey), dwellings were constructed by laying logs horizontally overtop of each other and filling in the gaps with "chips and mud".

Historically log cabin construction has its roots in Scandinavia and Eastern Europe. Although their origin is uncertain, the first log structures were probably being built in Northern Europe by the Bronze Age (about 3500 BC). C. A. Weslager describes Europeans as having:

By stacking tree trunks one on top of another and overlapping the logs at the corners, people made the "log cabin". They developed interlocking corners by notching the logs at the ends, resulting in strong structures that were easier to make weather-tight by inserting moss or other soft material into the joints. As the original coniferous forest extended over the coldest parts of the world, there was a prime need to keep these houses warm. The insulating properties of the solid wood were a great advantage over a timber frame construction covered with animal skins, felt, boards or shingles. Over the decades, increasingly complex joints were developed to ensure more weather tight joints between the logs, but the profiles were still largely based on the round log.