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Subfamily Eurycephalinae

The Wide-headed Hominids

  • Class Mammalia
  • Subclass Placentalia
  • Order Primates
  • Family Hominidae
  • Subfamily Eurycephalinae
    • Dwarf - Anthropus robustus
    • Human - Anthropus gracilis
    • Troll - Giganthropus trogl

Eurycephalines are one of the two subfamilies of Family Hominidae. Their name means "wide-heads" because their skulls are wider and rounder than those of the other subfamily, the dolicocephalines. The two subfamilies of Hominidae represent two different strategies for dealing with the expanded, extended development of the brain.

Eurycephalines have a long gestation period (around 300 days) and young are born comparatively well developed and with large, round heads. This allows much (though not all) of brain development to occur protected within the womb and for the skull to be more developed by birth and for the skull to be hardened and closed by 3 years.

However the large head at birth is a considerable difficulty in the birthing process. The characteristic wide hips of adult female eurycephalines are a result of the widening of the pelvic girdle and birth canal to ease this. Even so, birthing is probably more dangerous to eurycephaline mothers than to any other mammal.

However, this does mean eurycephaline infants are significantly more robust than dolicocephalines, and do not require as intensive care. Eurycephaline infant mortality rates are often less than 1 in 10, and sometimes 1 in 50 or even lower. Eurycephalines also twin regularily with rates of multiple births around 1 or 2 in 40 (in contrast to dolicocephalines who almost never have twins).

For most of the evolution of eurycephalines, as seperate from dolicocephalines, raising young has been costly in time and energy compared to the latter group, and so eurycephalines, while certainly having a pair-bond drive, never needed to develop it to the extreme degree of dolicocephalines. Polygyny (one male with more than one female mates) has almost always been present (though never universal) among eurycephaline species.

The hominid family as a whole had also moved in the direction of pair-bonding and two way selection before the split between the two subfamilies, and eurycephalines have continued that trend. But lacking the universal pair-bond and its extremely elaborate courtship rites (which are deeply tied into the neurophysiology of dolicocephalines), eurycephalines have remained a closer to the standard model of selection by females from among male competition.

For several reasons eurycephalines have more sexual dimorphism, including female structual changes for childbirth, and more male competition and less elaborate courtship behaviors than dolicocephalines. Sexual dimorphisms of eurycephalines not shared by dolicocephalines include, among females: a widened pelvic girdle (and thus hips) and enlarged mammary tissue (breasts). Male eurycephalines differ from dolicocephalines mostly in having less physical neoteny than either dolicocephalines or eurycephaline females: including greater size and musculature, deepened voices, and greater body hair (including facial hair).

Dwarves (Anthropus robustus) are notably different from other eurycephalines in some ways. They evolved in the near-polar mountains of the Iirîk Kata'at, which increased the support needed by infants. But dwarf evolution adapted to this increased need very differently than dolicocephalines had before. The have developed a family structure that includes more males than females, in which the extra males provide additional support to the family.

This article has Design Notes: Eurycephalinae/Notes

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