The chronological properties of otoliths are unparalleled in the animal world, allowing accurate estimates of age and growth at both the daily and the yearly scale. Based on the successes of calcified structures as environmental proxies in other taxa, it was logical that researchers should attempt to link otolith biochronologies with otolith chemistry. With the benefit of hindsight, this anticipation may have been naive. For instance, the concentrations of many elements are lower in the otolith than in corals, bivalves, seal teeth, or the other bony structures of fish, making them less than ideal for elemental analyses. Nevertheless, there is growing interest in the use of otolith chemistry as a natural tag of fish stocks. Such applications are directed at questions concerning fish populations rather than using the fish as a passive recorder of the ambient environment and do not rely upon any explicit relationship between environmental variables and otolith chemistry. The questions that can be addressed w...

Otoliths, increments, and elements: keys to a comprehensive understanding of fish populations?

The early-stage annual rings in otoliths from some cold-temperate fish consist of thin growth bands, the number of which corresponds to that of the days in a year. This indicates that growth takes place by daily increments. Other recurrent patterns show a fortnightly and monthly periodicity. Spawning rings are microscopically distinguishable from winter rings.

https://science.sciencemag.org/content/sci/173/4002/1124.full.pdf

Fish Otoliths: Daily Growth Layers and Periodical Patterns

A review of mammalian age determination methods

Development of the dentition is critically integrated into the life cycle in living mammals. Recent work on dental development has given rise to three separate lines of evidence on the evolution of human growth and aging; these three, based on several independent studies, are reviewed and inte- grated here. First, comparative study of living primate species demonstrates that measures of development (e.g., age of emergence of the first permanent molar) are highly correlated with the morphological attributes brain and body weight (as highly as r = 0.98, N = 21 species). These data predict that small-bodied, small-brained Australopithecus erupted M, at 3-3.5 years and possessed a life span comparable to that of a chimpanzee. Second, chronologi- cal age at death for three australopithecines who died at or near emergence of MI is now estimated as -3.25 years based on incremental lines in teeth; this differs substantially from expectations based on human growth schedules (5.5-6 years). Third, developmental sequences (assessed by the coefficient of variation of human dental age) observed in gracile Australopithecus and great apes diverge from those of humans to a comparable degree; sequences become more like modern humans after the appearance of the genus Homo. These three lines of evidence agree that the unique rate and pattern of human life history did not exist at the australopithecine stage of human evolution. It is proposed that the life history of early Homo matched no living model precisely and that growth and aging evolved substantially in the Hominidae during the last 2 million years.

/pdf/dental-development-and-the-evolution-of-life-history-in-1krcask1p1.pdf

A. C. Neville

Papers

Daily growth layers in animals and plants