Language delays are often identified when a child strays from the expected developments in the timeline of typical speech and language developmental milestones that researchers agree on. Children can stray slightly from the confines of the expected timeline; however, if a child is observed to be largely straying from the expected timeline, the childs caretaker should consult with a medical specialist. Timeline of typical speech and language developmental milestones
This timeline only provides a very general and brief outline of expected developments from birth to age five, individual children can still exhibit varying development patterns as this timeline only serves as a general guideline. This timeline is only one model, other models regarding language development exist. The development of language remains a theoretical mystery. Around 2 months, babies can make "cooing" sounds.Around 4 months, babies can respond to voices.Around 6 months, babies begin to babble and respond to names.Around 9 months, babies begin to produce mama/dada - appropriate terms and are able to imitate one word at a time.Around 12 months, toddlers can typically speak one or more words. They can produce two words with meaning.Around 15 months, toddlers begin to produce jargon, which is defined as "pre-linguistic vocalizations in which infants use adult-like stress and intonation".Around 18 months, toddlers can produce 10 words and follow simple commands.Around 24 months, toddlers begin to produce 2-3 words and phases that use "I", "Me", and "you", indicating possession. They are about 25% intelligible.Around 3 years, toddlers are able to use language in numerical terms.
Certain combinations of mutations in the given progenitor cell ultimately result in that cell (also called a cancer stem cell) displaying a number of abnormal, malignant cellular properties that, when taken together, are considered characteristic of cancer, including:

the ability to continue to divide perpetually, producing an exponentially (or near-exponentially) increasing number of new malignant cancerous "daughter cells" (uncontrolled mitosis);
the ability to penetrate normal body surfaces and barriers, and to bore into or through nearby body structures and tissues (local invasiveness);
the ability to spread to other sites within the body (metastasize) by penetrating or entering into the lymphatic vessels (regional metastasis) and/or the blood vessels (distant metastasis).If this process of continuous growth, local invasion, and regional and distant metastasis is not halted via a combination of stimulation of immunological defenses and medical treatment interventions, the result is that the host has a continuously increasing burden of tumor cells throughout the body. Eventually, the tumor burden increasingly interferes with normal biochemical functions carried out by the hosts organs, and death ultimately ensues. Carcinoma is but one form of cancer—one composed of cells that have developed the cytological appearance, histological architecture, or molecular characteristics of epithelial cells. A progenitor carcinoma stem cell can be formed from any of a number of oncogenic combinations of mutations in a totipotent cell, a multipotent cell, or a mature differentiated cell.