Five Mass Extinctions and the Sixth (Anthropogenic) Extinction
Biology · Biodiversity and Conservation · NEET
Life on Earth has faced five natural episodes of mass extinction over the last 3 billion years, long before humans existed. The "Sixth Extinction" is happening now, and its one key difference is the rate: current species extinction is 100 to 1000 times faster than in pre-human times, driven by human activity, which is why it is called anthropogenic. Memory hook: FIVE were natural, the SIXTH is us, and the exam answer is always the number "100 to 1000 times faster."
Timeline showing five natural mass extinctions across more than 3 billion years and the ongoing sixth (anthropogenic) extinction, whose defining feature is a species-loss rate 100 to 1000 times faster than in pre-human times.
Your doubts, answered
What is the ONE difference between the sixth extinction and the previous five mass extinctions?
The difference is the RATE, not the cause of death itself. NCERT states the current species extinction rates are estimated to be 100 to 1,000 times faster than in the pre-human times, and our (human) activities are responsible for the faster rates. NEET repeatedly tests exactly this line, so memorise the number 100 to 1000 times.
Why is the sixth extinction called the 'anthropogenic' extinction?
'Anthropogenic' means caused by humans. The five earlier mass extinctions happened naturally, even before humans appeared on Earth. The sixth is different because human activities (habitat loss, over-exploitation, alien species, co-extinctions) are driving it, so it is named the anthropogenic extinction.
How many mass extinctions were there before humans, and over what time?
There were five episodes of mass extinction of species during the long period of more than 3 billion years since the origin and diversification of life on Earth. All five were natural events that occurred before humans appeared, so the sixth (present, human-caused) is separate from these five.
Does the sixth extinction mean the extinction rate is very high or zero?
It is very high, not zero. A common trap option says the net rate is zero, which is false. The rate is 100 to 1000 times faster than pre-human times. Around 15,500 species worldwide are facing the threat of extinction, showing the rate is accelerating, not stopping.
Is the number '100 to 1000 times faster' compared to the earlier five extinctions or to pre-human times?
It is compared to PRE-HUMAN times, not to the earlier mass-extinction episodes. NCERT's exact wording is 'faster than in the pre-human times.' NEET options sometimes swap this to 'faster than previous episodes' to trick you, so read the comparison word carefully.
⚠️ The NEET trap ✗ The current extinction rate is nearly 10 times faster than in previous episodes. ✓ The current (sixth) extinction rate is 100 to 1000 times faster than in PRE-HUMAN times, and human activities are responsible. 🧠 NTA hides two traps in one option: the WRONG number (10 vs 100-1000) and the WRONG comparison (previous episodes vs pre-human times). Lock in both: the figure is 100-1000 and the reference is pre-human times.
Real NEET questions
NEET 2026
Since the origin and diversification of life on Earth, there have been five episodes of mass extinction of species. How is the sixth extinction, which is in progress, different from the previous episodes?
A · The present net species extinction rate is zero.
B · The current species extinction rate is nearly 10 times faster than in previous episodes.
C · The present species extinction rates are 100 to 1000 times faster than in the pre-human times. ✓
D · The current species extinction rates are far lower than those in previous episodes.
Solution: The difference between the ongoing Sixth Extinction and the five previous mass extinctions lies in the RATE: current rates are 100 to 1,000 times faster than pre-human times, and human activities drive this acceleration. Option A is false (the rate is high, not zero), option B understates and mis-compares the figure, and option D is the opposite of the truth. NCERT Class XII, Ch 13, p.222.
Solved Biodiversity and Conservation NEET PYQs
Try the real previous-year questions from this chapter — each with the answer and a full solution.
How many mass extinctions have happened before the sixth?
Five. NCERT says there were five episodes of mass extinction of species over more than 3 billion years since life originated on Earth, all before the human-driven sixth extinction.
What is the anthropogenic (sixth) extinction?
It is the present, ongoing loss of species caused mainly by human activities. It is called anthropogenic because 'anthropo' means human. Its extinction rate is 100 to 1000 times faster than pre-human times.
What is the exact NEET fact I must remember?
Current species extinction rates are estimated to be 100 to 1,000 times faster than in the pre-human times, and human activities are responsible for the faster rates.
How many species are facing the threat of extinction now?
More than 15,500 species worldwide are facing the threat of extinction according to NCERT, which shows how fast biodiversity is declining today.
Are amphibians more vulnerable to extinction?
Yes. NCERT notes that extinctions across taxa are not random and some groups, like amphibians, appear to be more vulnerable to extinction than others.
