article_snippet: But Nora Lewin from Michigan State Univerity's zoology department   wanted to know if these long-accepted biological markers would support what Nora Lewin from Michigan State Univerity's zoology department   was seeing in the field.
article_snippet: This internal 'clock' makes it difficult to keep most cells growing in a laboratory for more than a few cell doublings.
article_snippet: But Ms Lewin also noted a couple of interesting twists.
article_snippet: the team research found no correlation between the amount of food and the size of the biological marker. '
article_snippet: we think it's less about genetics and more influenced by the environment, but we just need to keep searching for the right environmental factors.'
article_snippet: The results are published in the journal of Biology Letters.