S M Platek | PubMed Health

PubMed2002

The fireside hypothesis: was there differential selection to tolerate air pollution during human evolution?

It is believed that sometime around 1.9 million years ago early hominid ancestors began to migrate out of Africa. Migration north and away from the equator would have forced early humans to encounter seasonal fluctuations in temperature. As a means of adapting to cold climates, the use of fire undoubtedly played an important role. We hypothesize that progressive exposure to toxic airborne particles produced from combustion created selective pressure to develop an adaptation to the inhalation of smoke. In this paper we test this hypothesis using archival data on the incidence of different cancers among geographically distinct human populations. As predicted from evolutionary theory, the incidence of lung cancer is inversely proportional to the ostensible reliance on fire of geographically different groups during human evolutionary history.

Adaptation, Physiological↗

PubMed2001

Sex differences in olfactory self-recognition.

This study investigated sex differences in the ability to recognize one's own body odor accompanied by an attempt to account for variance in this ability by comparing ratings of self-body odor and other odors on a visual analog scale (VAS). Whereas over half (59.4%) of the females were able to identify their own odor, only one out of 18 (5.6%) males were able to recognize their own odor. Females rated their own secretions as significantly lower on a pleasant-positive factor than males rated their own odors (axillary secretions), but there was no difference in ratings between those who could and those who could not identify their own odor. The dimensions tapped by the VAS used in this study do not seem to account for the ability to identify one's own body odors.

Adolescent↗

PubMed2000

Anti-sense oligonucleotides, for progestin receptors in the VMH and glutamic acid decarboxylase in the VTA, attenuate progesterone-induced lordosis in hamsters and rats.

Immunocytochemical (ICC) staining for progesterone (P) receptors (PRs) and glutamic acid decarboxylase (GAD), the enzyme responsible for GABA production, reveal that there are many PRs in the ventral medial hypothalamus (VMH) and many GAD containing neurons in the ventral tegmental area (VTA). To investigate P's action on lordosis in the VMH and VTA, anti-sense oligos specific to PRs and GAD(65&67) were intracerebrally infused into the VMH and VTA of 24 ovariectomized hamsters and 40 ovariectomized rats. Estradiol benzoate (2 microg) primed hamsters and rats were infused to the VMH and the VTA with either PR (250 ng/1.0 microl infusion) or GAD (500 ng/1.0 microl infusion) anti-sense oligos, their scramble controls, or saline vehicle at hour 0 and again at hour 24. At hr 44, rodents were subcutaneously injected with P (500 microg) and were tested for sexual receptivity with a male 4 h later. There were significant reductions in lordosis of hamsters and rats following PR anti-sense infusions to the VMH compared to scrambled or vehicle control infusions. Effects of PR anti-sense to the VMH were not different from combined VMH and VTA PR anti-sense infusions; however, VMH infusions reduced lordosis compared to VTA-only anti-sense infusions. GAD anti-sense infusions reduced lordosis when infused into the VTA, compared to scrambled or saline vehicle infusions. Lordosis responsiveness following VTA GAD anti-sense infusions was not different from combined VMH and VTA infusions, but VTA infusions of GAD anti-sense reduced lordosis compared to VMH-only anti-sense infusions. These data suggest that in the VMH, PRs are important for P-facilitated lordosis, whereas in the VTA, GABAergic neurons may be an important substrate for mediating P's actions on lordosis of rodents.

Animals↗