Too late: Extinctions
When an organism's environmental conditions change such that their death rate continues to exceed their birth rate, extinction of the species is inevitable. It is estimated that about fifty species per day are becoming extinct due to environmental degradation (e.g. clearing of tropical rainforest and draining of wetlands). This creates imbalances in food chains within delicate ecosystems, and interrupts life cycles. Current conservation practices Nowadays, the preparation of an environmental impact statement is essential
for any new developments or mining project. Also conservation of specific
habitats in national parks and wilderness areas aims to maintain natural
environmental conditions essential for survival of endangered species.
Zoos, and herbariums, now take a more proactive role in wildlife conservation
of animals and plants. Extinction of many other organisms particularly plant, insect, frog and bird species, is attributable to more indirect and less obvious human practices. Humans' impact on the environment (see Impact on environment: Human) in turn affects availability of food, nesting sites and protective shelter, and causes direct poisoning through pollution.
Why did these prolific and successful animals die out? Let's first discuss how scientists find out such answers! On the basis of observations, scientists construct an hypothesis (an educated guess). Predictions based on this hypothesis (e.g. "if this is true, then I'd expect...") suggest further experimentation, or exploration to look for "missing pieces of the puzzle". If, after further testing, the hypothesis is still undisputed, a theory is constructed, though "scientific truth" or "fact" can never be proven - only disproven. A theory is "the best explanation we have, given the evidence currently available". Theories can change dramatically with new evidence (what did Columbous do to test the "world is flat" theory?) Hypotheses for the dinosaurs' extinction
More evidence such as plant fossils from the same geological time might help support one particular hypothesis. However, the "truth" is unknown.
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