Storing sperm and Egg cells to later create babies when desired.
Parents controlling the baby sex that is produced.
Answer:
According to the current fossil record, scientists believe that the life on earth began about 3.5 billion years ago.
Answer:
In uranium-lead dating, for instance, the radioactive decay of uranium into lead proceeds at a reliable rate. Based on the very old zircon rock from Australia we know that the Earth is at least 4.374 billion years old.
And that's how after rounding we know that earth is 4.5 years old.
