منابع مشابه
How many species are there on Earth?
This article surveys current answers to the factual question posed in the title and reviews the kinds of information that are needed to make these answers more precise. Various factors affecting diversity are also reviewed. These include the structure of food webs, the relative abundance of species, the number of species and of individuals in different categories of body size, along with other ...
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How many basic tastes are there? Most people list four: sweet, sour, salty and bitter. Those with a background in the chemosensory sciences usually add a fifth, umami. But why stop there? There is growing evidence that there are more—perhaps many more. The idea that there are four basic tastes goes back at least as far as ancient Greece, so if there are more than four basic tastes why haven't t...
متن کاملHow many species are there?
'How many species are there' is a question receiving more attention from biologists and reasons for this are suggested. Different methods of answering this question are examined and include: counting all species; extrapolations from known faunas and regions; extrapolations from samples; methods using ecological models; censusing taxonomists' views. Most of these methods indicate that global tot...
متن کاملHow many words are there?
The commonsensical assumption that any language has only finitely many words is shown to be false by a combination of formal and empirical arguments. Zipf's Law and related formulas are investigated and a more complex model is offered.
متن کاملHow Many Types Are There?
We consider an revealed preference based method which will partition consumer microdata into an approximate minimal number of preference types such that the data are perfectly rationalisable by standard utility theory. This provides a simple, nonparametric and theory-driven way of investigating unobserved preference heterogeneity in empirical data, and easily extends to any choice model which h...
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ژورنال
عنوان ژورنال: Science
سال: 2014
ISSN: 0036-8075,1095-9203
DOI: 10.1126/science.346.6207.311-f