✓ Accepted Answer
The theory of evolution by natural selection explains how species change over time. The core mechanism: within any population, individuals vary in traits. Some traits improve survival and reproduction in the current environment. Those individuals pass more genes to the next generation. Over many generations, the population shifts.
This isn't random chance. Natural selection is a sorting mechanism — it consistently favours traits that improve fitness in a given environment. But which traits help depends entirely on the environment. In a changing environment, evolution can happen surprisingly fast.
Evolution is supported by multiple independent lines of evidence: the fossil record showing gradual changes over time, genetic analysis showing shared ancestry, direct observation of evolution happening (bacteria developing antibiotic resistance, for example), and comparative anatomy showing homologous structures across species.
Humans share about 99% of our DNA with chimpanzees, about 85% with mice, and even about 60% with banana plants — we're not descended from chimps but share a common ancestor from about 6-7 million years ago.
by sphesihlemthethwa20344
· 75 upvotes
Climate change refers to long-term shifts in global temperatures and weather patterns. While Earth's climate has always varied naturally, since the Industrial Revolution human activities — primarily burning fossil fuels — have accelerated warming dramatically.
Burning coal, oil, and gas releases CO2 and other greenhouse gases. These gases trap heat from the sun within Earth's atmosphere — the greenhouse effect. Without any greenhouse gases, Earth would be a frozen wasteland. With too many, temperatures rise beyond what ecosystems and human society can adapt to quickly.
Since 1880, global average temperature has risen about 1.2°C. This may sound small but represents enormous energy added to the climate system. Effects include more frequent and intense extreme weather events, rising sea levels from melting ice sheets, disrupted ecosystems, and threats to agriculture and water supplies.
The scientific consensus is overwhelming — 97% of climate scientists agree on the human cause. The disagreement is political, not scientific. The question is how fast we transition to clean energy and whether we can limit warming to 1.5-2°C above pre-industrial levels.
by nadinefrancis68745
· 7 upvotes