About 160 years. After Charles Darwin came out with his theory people have been debating it.
As we can see in the pedigree, both of the parents do not possess the trait, but one of the four offspring (marked with red) is expressing the trait.
Since the trait is recessive, the only way that is possible that the parents who do not possess the trait to have the offspring with the trait is that the parents are heterozygous for the trait. Meaning that both of the parents have one dominant allele and one recessive allele.
Microorganisms such as bacteria can be removed by disinfection. Certauns substances called biocides are addes to water to make it pure. Purification can also be done by UV-light .
pylometrics increases muscle strength and can improve coordination, strength, & speed