Age determination (biology)

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Age determination of living beings includes the methods of determining the age of animals and plants , which is usually not clearly ascertainable . As a rule, only an approximate age can be derived here, which is why the term age estimate is used more often .


Different body characteristics can be used to determine the age of animals if one knows their behavior over time. An age estimate is usually flawed, but for wildlife biologists or veterinarians it is often the only means of giving an approximate age.

Investigation procedure:

  • Measurements of size and weight : For young animals, i.e. animals that are still growing, you can read off the age by measuring the body length or certain body sections, provided you have appropriate reference data. Most reptiles , like fish , grow throughout their life. Therefore, height and age correlate.
  • Tooth age determination : Due to the relative constancy of the change of teeth in mammals and the wear and tear of the teeth , the dentition changes; see also: Tooth Age Estimation
  • Determination of bone age
  • Age determination based on the scales : In areas with scales, fish with scales show " annual rings " (annuli), which can often be counted without any further treatment, from which the exact age results. Something similar can be achieved with vertebral bodies, gill cover bones, etc., but especially with the "ear stones" (otoliths, S. Statolith ), which grow through external attachment and therefore show particularly clear growth zones. The Otolithologie is because the ear stones can be used (by the more specific form) and in determining the phylogenetic relationship and therefore a science discipline. Under certain circumstances, microscopic methods can also be used to identify daily growth zones - for example in the case of Paleozoic coral fossils, where it could be concluded that a year then had more than 400 days.
  • Lens weight : Since the lens of the eye grows for a long time, its mass can be determined by weighing and compared with reference data.
  • Plumage : With birds you can at least make a rough assignment based on the plumage (young birds, adult birds).
  • Bursa depth : In birds, since the bursa fabricii shows an age involution , the age can be determined by probing the depth of the cavity of this organ.
  • Horn rings : In horn-bearing ruminants , the metabolic stress caused by pregnancy results in different growth zones on the horn that are comparable to tree rings. Since there is usually one pregnancy per year, a rough age determination can also be carried out.
  • Ends : In antler-bearing ungulates an estimate of age follows on the ends, so the forks of the antlers

In archeozoology  - this also applies accordingly to anthropology and forensics on humans - there are also methods for examining non- decomposing or slowly decomposing body components such as horny substance ( hair , claws / nails , antlers and horns), bones or teeth. All these structures show signs corresponding to the annual rings, which can be microscopically evaluated in sections and sections and provide information about the age at which fossil creatures died. In addition, there are the methods that provide information about the age of the fossil and are dealt with in the article Age determination (archeology) .


The age of trees is determined with the help of annual rings , which is also common in the dating of fossil woods in dendrochronology .

The oldest tree on earth is believed to be the Old Tjikko spruce in Sweden. It reproduces clonally, the oldest part of the root, which is not connected to the tree that lives today, was determined by radiocarbon dating to around 9550 years. In the Inyo National Forest in California's White Mountains there are long-lived pines , the oldest known specimen of which was dated to 5062 years in 2012, converted to the year 2012. It is considered the oldest non-clonal tree. The dating of a 7240-year-old traditional Japanese cedar on Yakushima could not be proved. The oldest tree in Europe is known to be a pedunculate oak in granite (Bulgaria) with 1640 years, and Fortingall Yew in Perth and Kinross (Scotland) with an estimated 3000 to 5000 years. Besides conifers (such as Lagarostrobos franklinii , whose rhizomes can be up to 10,000 years old), ginkgo and fig trees are known for their great age.

Age determinations about the growth in thickness are not very meaningful, the thickest tree on earth, El árbol del Tule in Mexico, is estimated to be "only" 1200-3000 years, and almost all of the thousand - year - old trees in Europe can be found in the range of 300 to 600 years, In particular, wood that grows quickly, such as linden , beech or oak, is considered unreliable. Besides conifers should chestnut and olive plants such as the olive among the trees of Europe, reaching the highest age.

See also: Distinctive and old trees

For other plants there are seldom direct plant morphological criteria, and age determinations are more or less indirect. One example is the most extensive creatures on earth, a (previously known) Hallimasch (hat mushroom) in the Malheur National Forest (Oregon, USA) of at least 2,400 years, the age of the diameter of witches ring was calculated after the local stocks than on genetic testing a living being were recognized.

As much as trees are overestimated, perennials are underestimated. Slow-growing plants, such as the typical cushion plants of barren vegetation zones , or spring flowers reach an amazing age. For example, clumps of liverwort with a diameter of just under a meter have been found that are probably several hundred years old. Plants that have a strong vegetative spread - such as nettles or bamboo - can reach old populations and cover astonishing distances.

See also

Individual evidence

  1. message on
  2. Rocky Mountain Tree Ring Research: Database of ancient trees (January 2013)
  3. Guinness Book of Records , cited from information on the forest ecosystem , Schutzgemeinschaft Deutscher Wald ,