The amount of evidence required to declare a new species of human is a complex and subjective matter. There is no single, definitive answer, as the criteria for establishing a new species can vary depending on the specific case. However, some of the key factors that are typically considered include:

- Morphological evidence: This refers to the physical characteristics of the individual or individuals in question. Some of the key morphological features that are often used to distinguish between different species of humans include skull shape, dental features, and limb proportions.

- Genetic evidence: This refers to the genetic differences between the individual or individuals in question and other related species. Some of the key genetic markers that are often used to study human evolution include mitochondrial DNA and nuclear DNA.

- Behavioral evidence: This refers to the behavioral differences between the individual or individuals in question and other related species. Some of the key behavioral characteristics that are often used to study human evolution include tool use, social organization, and language.

- Ecological evidence: This refers to the environment in which the individual or individuals in question live. Some of the key ecological factors that are often used to study human evolution include climate, vegetation, and food resources.

In addition to these four main lines of evidence, other factors that may be considered when declaring a new species of human include historical and archaeological evidence. Ultimately, the decision of whether or not to declare a new species of human is a complex one that must be made on a case-by-case basis.