Neanderthals constructed complex subterranean buildings 175,000 years ago, a new archaeological discovery has found. Neanderthals built mysterious, fire-scorched rings of stalagmites 1,100 feet into a dark cave in southern France—a find that radically alters our understanding of Neanderthal culture.

Species problem


The species problem is a mixture of difficult related questions that often come up when biologists define the word "species". There are a wide range of approaches to defining how we identify species and how species function in nature; each approach is known as a species concept. The number and types of species concepts which exist are constantly changing, but there are at least 26 recognized species concepts. Biological reality means that a definition that works well for some organisms (e.g., birds) will be useless for others (e.g., bacteria) particularly due to concerns regarding if the species reproduces asexually or sexually. The scientific study of the species problem has been called microtaxonomy. One common, but sometimes difficult, question is how best to decide which species an organism belongs to, because reproductively isolated groups may not be readily recognizable, and cryptic species may be present. There is a continuum from total reproductive isolation to panmixis. Populations can move forward or backwards along the interbreeding continuum, at any point meeting or failing the criteria for different species concepts. Thus, it is difficult to define reproductive isolation. Some separately evolving groups may continue to interbreed to some extent, or begin interbreeding again after a period of isolation, and it can be a difficult matter to discover whether this hybridization affects the long-term genetic make-up of the groups. Many of the debates on species touch on philosophical issues, such as nominalism and realism, as well as on issues of language and cognition. The current meaning of the phrase "species problem" is quite different from what Charles Darwin and others meant by it during the 19th and early 20th centuries. For Darwin, the species problem was the question of how new species arose: speciation.


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