TOEFL Sample Questions with Answers

The Domestication of Fire by Early Humans

The controlled use of fire represents one of the most transformative developments in the history of our species. Archaeological evidence suggests that Homo erectus, an early human ancestor, may have used fire as far back as 1.5 million years ago at sites in East Africa, though conclusive proof of deliberate fire-making does not appear until roughly 400,000 years ago in sites across Europe and Asia. Scholars distinguish between opportunistic use — exploiting naturally occurring fires caused by lightning strikes — and true domestication, which involves reliably igniting, maintaining, and transporting fire.

The consequences of fire domestication were far-reaching. Cooking, enabled by fire, dramatically altered human nutrition: heat breaks down fibrous plant material and denatures proteins in meat, making calories substantially easier to extract. Anthropologist Richard Wrangham has argued that the energy savings from cooked food drove the dramatic reduction in gut size and the corresponding expansion of the brain observed in the fossil record between Homo erectus and anatomically modern humans. Whether or not Wrangham's specific hypothesis is correct, it is widely accepted that cooked food represents a higher-quality diet that supported the metabolic demands of a larger brain.

Fire also reshaped social behavior. Light extended the usable hours of the day, allowing activities previously confined to daylight to continue into the evening. Campfires created focal points around which early communities gathered, potentially accelerating the development of language and cooperative social bonds. Predators, many of which hunted at night, were deterred by fire, reducing the threat to sleeping groups. These converging advantages meant that populations capable of controlling fire gained significant survival and reproductive benefits over those that could not.

[Professor speaking to an undergraduate ecology class]

“Okay, so last time we covered primary succession — what happens when life colonizes a completely barren substrate, like fresh lava. Today I want to focus on secondary succession, which is actually far more common. Secondary succession occurs after a disturbance — a forest fire, a flood, or even agricultural abandonment — where the soil and seed bank remain intact. That's the key difference: the biological legacy is still there.

Now, the classic example everyone uses is the abandoned agricultural field. You leave a field alone, and within a year you have annual weeds — plants that complete their entire life cycle in a single growing season. Fast-growing, lots of seeds. They're what ecologists call early successional species, or pioneers. But here's the interesting part: those pioneers actually change the environment in ways that make it less suitable for themselves and more suitable for the next group — perennial grasses and shrubs. So there's an inherent self-replacement happening.

Eventually, in many temperate regions, you'll get shrubs giving way to fast-growing, light-demanding trees — like birch or aspen. And those, over decades, get replaced by shade-tolerant species like oak or maple. That final, theoretically stable community is what ecologists call the climax community. I should note — and this is important for your exam — the climax community concept has been debated. Some ecologists argue it's an idealized endpoint that rarely exists perfectly in nature because disturbances keep interrupting the process. But it remains a useful conceptual framework.”