Did the control of fire to , ? Or did merely use it to begin dominating the world? Was cooking the seminal event in the appearance of humans? Those questions may not be definitively answered in my lifetime, and led to the somewhat uncertain title of this chapter. Highly transformative developments coincided with the appearance and dispersal of , which was a radical break from all that came before – biologically, technically, and culturally – and strongly implies great cognitive enhancements. I believe that the control of fire and cooking would leave deep cultural and biological impacts on the human journey, and because barely changed during its nearly two-million year tenure on Earth, both in biology and in Acheulean artifacts, I favor Wrangham’s hypothesis, at least until the Next Big Finding. Just as Einstein said that and that his theories would one day become obsolete, but that their best parts would survive in the new theories, I suspect that significant aspects of Wrangham’s hypothesis will live on in successor hypotheses, and other scientists have been following Wrangham’s lead.
The derision was loud from Wrangham’s colleagues…until evidence of was found at in South Africa by using new tools and techniques. The chortling is subsiding somewhat and scientists are now looking for the faint evidence, and long-disputed evidence of 1.5-1.7 mya controlled fires is being reconsidered, although his hypothesis is still widely considered as being only "mildly compelling" at best. New tools may push back the control of fire to a time that matches Wrangham’s audacious hypothesis. Wrangham cited the Expensive-Tissue Hypothesis as partially supporting the Cooking Hypothesis, but , the energy to power the human brain may not have solely derived from cooked food’s energy benefits. Wrangham has cited numerous lines of evidence, one of which is a that has to find honeybee hives and smoke them out; the humans get the honey and the honeyguide gets the larvae and wax. According to recent molecular evidence, the evolutionary split of the honeyguide from its ancestors happened up to three mya, which supports the early-control-of-fire hypothesis. There is great controversy regarding these subjects, from recent findings that to scientists making arguments that to the social impacts of campfires. This section of this essay will probably be one of the first to be revised in future versions, as new evidence is adduced and new hypotheses are proposed.
After the dinosaurs, empty niches filled with animals that looked remarkably like dinosaurs, if we squinted. Most large browsing weighed in the five-to-seven metric ton range. By the late Paleocene, appeared in North America and China and attained about rhinoceros size, to be supplanted in the Eocene by larger , and in Oligocene Eurasia lived the largest land mammals of all time, including the truly dinosaur-sized . The largest yet found weighed 16 metric tons and was about five meters tall at the shoulders and eight meters in length. Even a might have thought twice before attacking one of those. It took about , and for the succeeding 40 million years, the maximum size remained fairly constant. Scientists hypothesize that mammalian growth to dinosaurian size was , including continent size and climate, and .
With the success of the end-Cretaceous bolide hypothesis, there was a movement in some circles to explain mass extinctions with bolide events, . If bolide events were responsible for all mass extinctions, then the , galactic explanation might still have relevance. Even though an end-Permian bolide event was unveiled with great fanfare and media attention in 2001, it does not appear to be a valid extinction hypothesis today, and invoking bolide impacts to explain mass extinction seems to have been a passing fad that has seen its best days. The oxygen hypothesis for explaining extinctions, evolutionary novelty, and radiations is similarly called a current fashion in some circles, and time will tell how the hypothesis fares, although it seems to have impressive explanatory value.
Myth 1: Hypotheses Become Theories Which Become Laws
This myth deals with the general belief that with increased evidence thereis a developmental sequence through which scientific ideas pass on theirway to final acceptance.
To succeed in this science course and, more specifically, to answer some of thequestions on the first exam, you should be familiar with a few of the concepts regardingthe definition of science, scientific thinking, and the methods of science. Most textbooksdo an inadequate job of this task, so this essay provides that information. Thisinformation in its present form is not in your textbook, so please read it carefully here,and pay close attention to the words in boldface and the definitions in italics.
A study of the history of the scientific method will reveal that it was not invented by one single person. Rather, its development is best defined as the accumulation of knowledge that led to scientific analysis and understanding.
Around 200 BC, a catalogued library was established in Alexandria in Egypt. Another important event occurred in 800 AD when Muslim scientists started conducting controlled experiments, which would become part and parcel of scientific investigation. In 1265 Roger Bacon redefined the scientific method by using observation, hypothesis and experiments.
The history of the scientific method in the 1650s was marked by the publication of numerous scientific journals. Using hypothesis and prediction, Isaac Newton was able to formulate his theory of gravity.
This true understanding of nature is what Icall ``scientific truth'' in this text to distinguish it from other definitionsof truth as in religious truth, for example.
What is scientific thinking? At this point, it is customary to discussquestions, observations, data, hypotheses, testing, and theories, which are the formalparts of the scientific method, but these are NOT the most important components of thescientific method. The scientific method is practiced within a context of scientificthinking, and scientific (and critical) thinking is based on three things: using empiricalevidence (empiricism), practicing logical reasonsing (rationalism), and possessing askeptical attitude (skepticism) about presumed knowledge that leads to self-questioning,holding tentative conclusions, and being undogmatic (willingness to change one's beliefs).These three ideas or principles are universal throughout science; without them, therewould be no scientific or critical thinking. Let's examine each in turn.
Myth 2: A Hypothesis is an Educated Guess
The definition of the term hypothesis has taken on an almost mantra- likelife of its own in science classes.
If a hypothesis is always an educatedguess as students typically assert, the question remains, "an educatedguess about what?" The best answer for this question must be, that withouta clear view of the context in which the term is used, it is impossible totell.
The stepslisted for the scientific method vary from text to text but usuallyinclude, a) define the problem, b) gather background information, c) forma hypothesis, d) make observations, e) test the hypothesis, and f) drawconclusions.