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A method like this was used to determine the age of the Greenland shark, a large shark living in cold waters. "In 2016, a study based on 28 specimens that rang

A method like this was used to determine the age of the Greenland shark, a large shark living in cold waters. "In 2016, a study based on 28 specimens that ranged from 81 to 502 cm (2.7–16.5 ft) in length determined by radiocarbon dating of crystals within the lens of their eyes, that the oldest of the animals that they sampled, which also was the largest, had lived for 392 ± 120 years and was consequently born between 1504 and 1744" https://en.wikipedia.org/wiki/Greenland_shark https://en.wikipedia.org/wiki/Greenland_shark

pvaldes 7y ago
> had lived for 392 ± 120 years Is the same problem, I personally (is just my opinion) wouldn't discard that where 392 solid meals instead, one seal or reindeer at a time boosting grow periods between nape and nape, minus an unknown number of pregnancy events. Scientists are forced to publish something, anything, in short periods of time, so here we are. And is getting worse.
- bpodgursky 7y ago
  Radiocarbon dating wouldn't be affected by meal frequency, unless I'm missing something. It's just identifying the oldest material in the specimen.
  - pvaldes 7y ago
    We have two main different ways to attack the problem of age, and both have issues > But as scientists know the rate at which this isotope decays, it is a very useful marker in determining age... The older the creature, the less Carbon-14 you'd expect to find. They are registering decay in the level of carbon-14. The clock is adjusted for bone (storing this isotope as a more or less permanent crystalline mix of carbone and calcium). This is cartilage. And teeth in sharks last only for some period ranging between, lets say, two weeks and two years (100 days for a white shark or so). Somewhere inside this period, those pieces storing carbon-14 will fall and will need to be replaced in a few days. If the reserves are mobilised from vertebra to tooth, then you would expect to find much less carbon-14 than usual. Therefore you could conclude than the fish is much older than it really is. Counting the number and type of rings on vertebra is a different problem, and is affected by fasting and starving periods.
    - deleted 7y ago
      [deleted]
- kgwgk 7y ago
  How would those events change the crystals within the lens of their eyes?
  - pvaldes 7y ago
    Unlike us, fishes have continuous growing. And also unlike us, they do not use sugars. Its main source of energy is fat, that they store either in the whole body or in the liver. Sharks belong to the second group (something than was basic for the development of precision machines and robotics in fact). Being cold blooded species, fishes rely on the water temperature to warm itselves. When the temperature decreases under the viable range for its enzimatic gut activity, they stop eating, get sluggish and enter in "saving energy mode" until the circumstances got favourable again (instead to spend valuable resources chasing preys that they can't digest anymore). In a long migration through open sea they will cross extensive low-density preys areas and the result is similar. If the fat reserves eventually get depleted the fishes need to resort to its second and last source of energy: Proteins. They start burning muscle, recycling its proteins as fat and burning this fat. Fishes do this routinely when needed and can "de-grow" to some extent, shrink and recover quickly later. Sharks are particularly well adapted to alternate periods of feast and famine. In case of emergency, we can burn proteins in a similar way, but, unlike us, the weigh of aquatic animals is supported by water in part, so its skeletons are also reduced. Our skeletons are always saved until the last minute (We need it more than fishes need theirs). And this is the part used in carbon-14 tests. As proteins (like those in eye lenses) and fats are made of carbone, almost anything non indispensable in a fish body can be recycled and burn instead. Eyes are not essential structures for deep-water sharks (can rely in olfactory, electric and water pressure receptors instead), so if in a hurry, they can assign less resources for their maintenance. The result is that the eye lense will grow slower and with a lighter (cheaper) structure, therefore you have a more transparent area. A feasting period instead means some extra calcium (or other matherials) assigned to the eye maintenance. This is what makes the structure "readable" as a series of bands alternatively opaque and hyaline.
    - kgwgk 7y ago
      They are looking at those proteins in the nucleus of the lens of the eye for a reason. Didn’t you wonder why? “In vertebrates, the eye lens nucleus is composed of metabolically inert crystalline proteins, which in the center (i.e., the embryonic nucleus) is formed during prenatal development (6, 7). This tissue retains proteins synthetized approximately at age 0 – a unique feature of the eye lens that has been exploited for other difficult-to-age vertebrates (6, 8, 9).” https://ora.ox.ac.uk/objects/uuid:6c040460-9519-4720-9669-9911bdd03b09/download_file?file_format=pdf&safe_filename=Eye%2Blens%2Bradiocarbon%2Breveals%2Bcenturies%2Bof%2Blongevity%2Bin%2BGreenland%2Bshark.pdf&type_of_work=Journal+article https://ora.ox.ac.uk/objects/uuid:6c040460-9519-4720-9669-99... “Because the epithelial basement membrane (lens capsule) completely encloses the lens, desquamation of aging cells is impossible, and due to the complete absence of blood vessels or transport of metabolites in this area, there is no subsequent remodelling of these fibers, nor removal of degraded lens fibers. [...] The lens fibre cells in the nucleus of an adult lens are thought to be produced during early embryonic life [2]. The lens plate is formed in the 4 mm embryonal stage. The lens fibre cells degrade all membrane-bound organelles and the older lens cells become compressed into the nucleus of the lens by the continuous formation of new fibres at the surface.” https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0001529 https://journals.plos.org/plosone/article?id=10.1371/journal...

pvaldes 7y ago

> had lived for 392 ± 120 years Is the same problem, I personally (is just my opinion) wouldn't discard that where 392 solid meals instead, one seal or reindeer at a time boosting grow periods between nape and nape, minus an unknown number of pregnancy events. Scientists are forced to publish something, anything, in short periods of time, so here we are. And is getting worse.

bpodgursky 7y ago
Radiocarbon dating wouldn't be affected by meal frequency, unless I'm missing something. It's just identifying the oldest material in the specimen.
- pvaldes 7y ago
  We have two main different ways to attack the problem of age, and both have issues > But as scientists know the rate at which this isotope decays, it is a very useful marker in determining age... The older the creature, the less Carbon-14 you'd expect to find. They are registering decay in the level of carbon-14. The clock is adjusted for bone (storing this isotope as a more or less permanent crystalline mix of carbone and calcium). This is cartilage. And teeth in sharks last only for some period ranging between, lets say, two weeks and two years (100 days for a white shark or so). Somewhere inside this period, those pieces storing carbon-14 will fall and will need to be replaced in a few days. If the reserves are mobilised from vertebra to tooth, then you would expect to find much less carbon-14 than usual. Therefore you could conclude than the fish is much older than it really is. Counting the number and type of rings on vertebra is a different problem, and is affected by fasting and starving periods.
  - deleted 7y ago
    [deleted]
kgwgk 7y ago
How would those events change the crystals within the lens of their eyes?
- pvaldes 7y ago
  Unlike us, fishes have continuous growing. And also unlike us, they do not use sugars. Its main source of energy is fat, that they store either in the whole body or in the liver. Sharks belong to the second group (something than was basic for the development of precision machines and robotics in fact). Being cold blooded species, fishes rely on the water temperature to warm itselves. When the temperature decreases under the viable range for its enzimatic gut activity, they stop eating, get sluggish and enter in "saving energy mode" until the circumstances got favourable again (instead to spend valuable resources chasing preys that they can't digest anymore). In a long migration through open sea they will cross extensive low-density preys areas and the result is similar. If the fat reserves eventually get depleted the fishes need to resort to its second and last source of energy: Proteins. They start burning muscle, recycling its proteins as fat and burning this fat. Fishes do this routinely when needed and can "de-grow" to some extent, shrink and recover quickly later. Sharks are particularly well adapted to alternate periods of feast and famine. In case of emergency, we can burn proteins in a similar way, but, unlike us, the weigh of aquatic animals is supported by water in part, so its skeletons are also reduced. Our skeletons are always saved until the last minute (We need it more than fishes need theirs). And this is the part used in carbon-14 tests. As proteins (like those in eye lenses) and fats are made of carbone, almost anything non indispensable in a fish body can be recycled and burn instead. Eyes are not essential structures for deep-water sharks (can rely in olfactory, electric and water pressure receptors instead), so if in a hurry, they can assign less resources for their maintenance. The result is that the eye lense will grow slower and with a lighter (cheaper) structure, therefore you have a more transparent area. A feasting period instead means some extra calcium (or other matherials) assigned to the eye maintenance. This is what makes the structure "readable" as a series of bands alternatively opaque and hyaline.
  - kgwgk 7y ago
    They are looking at those proteins in the nucleus of the lens of the eye for a reason. Didn’t you wonder why? “In vertebrates, the eye lens nucleus is composed of metabolically inert crystalline proteins, which in the center (i.e., the embryonic nucleus) is formed during prenatal development (6, 7). This tissue retains proteins synthetized approximately at age 0 – a unique feature of the eye lens that has been exploited for other difficult-to-age vertebrates (6, 8, 9).” https://ora.ox.ac.uk/objects/uuid:6c040460-9519-4720-9669-9911bdd03b09/download_file?file_format=pdf&safe_filename=Eye%2Blens%2Bradiocarbon%2Breveals%2Bcenturies%2Bof%2Blongevity%2Bin%2BGreenland%2Bshark.pdf&type_of_work=Journal+article https://ora.ox.ac.uk/objects/uuid:6c040460-9519-4720-9669-99... “Because the epithelial basement membrane (lens capsule) completely encloses the lens, desquamation of aging cells is impossible, and due to the complete absence of blood vessels or transport of metabolites in this area, there is no subsequent remodelling of these fibers, nor removal of degraded lens fibers. [...] The lens fibre cells in the nucleus of an adult lens are thought to be produced during early embryonic life [2]. The lens plate is formed in the 4 mm embryonal stage. The lens fibre cells degrade all membrane-bound organelles and the older lens cells become compressed into the nucleus of the lens by the continuous formation of new fibres at the surface.” https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0001529 https://journals.plos.org/plosone/article?id=10.1371/journal...