For decades, the idea of “getting older” has been associated with round numbers: 60, 65 or retirement. However, Science has been questioning this simplistic view for some time.. Today, aging is studied not only as a matter of years completed, but as a measurable, uneven and deeply individual biological process. And the results are changing our collective perception of when old age really begins.
Aging is not linear
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One of the most relevant advances in this field comes from an extensive study led by researchers at Stanford University, published in Nature Medicine. Instead of just looking at external symptoms, the team analyzed the blood plasma of thousands of people to see how certain proteins change throughout life. These molecules act as indicators of the state of the tissues and the general functioning of the body.
The main conclusion was clear: aging does not occur progressively and constantly. The body can remain relatively stable for years and suddenly experience abrupt biological changes. The scientists identified three large “windows” or biological stagesseparated by moments of acceleration of the internal clock.
Three key biological stages
According to this analysis, adult life is organized into three main phases. The first corresponds to early and middle adulthoodapproximately between 34 and 60 years old. Although it is socially perceived as a stage of plenitude, researchers detected that around the age of 34 the first significant biological decline occurs. It is a silent change, barely perceptible, but it marks the end of biological youth.
The second stage, called late maturityextends from 60 to 78 years. During this period, many body functions remain relatively stable, especially if healthy habits are maintained. For science, this phase is not yet equivalent to old age, although this is culturally perceived in many countries.
The third and final stage begins, on average, at age 78. It is at this moment when the study places the beginning of old age from a biological point of view. From there, changes in plasma proteins indicate a deeper and more generalized transformation of the organism.
What happens in the body when entering old age
The transition to this final phase of aging is related to a decreased ability of the body to repair itself. DNA repair becomes less efficient, metabolism slows down, and systems that previously compensated for small damage no longer do so as effectively.
Among the most common changes associated with this stage are progressive loss of muscle mass, weakening of bones, reduced visual and hearing acuity, and alterations in sleep patterns. There is also a reduction in movement speed and greater difficulty recovering energy after exertion.
On a cognitive level, mild everyday memory problems may appear. These are not necessarily neurodegenerative diseases, but rather a reflection of the molecular and protein changes that affect the functioning of the brain over time.
Chronological age vs. biological age
One of the most important messages of this research is that Biological age does not always coincide with the age indicated on the DNI. Two 70-year-old people can be in very different biological phases, depending on factors such as genetics, lifestyle, level of physical activity, sleep or diet.
Therefore, scientists insist that Talking about “being older” solely based on age is becoming less and less accurate. From this perspective, many people considered socially older would still be, biologically, in a stage of late maturity and not in old age itself.
These findings also force us to rethink social concepts such as active aging or health prevention. If biological old age begins later than previously thought, It becomes even more important to invest in healthy habits for decades to delay that last part of the process.
Science does not deny the passage of time, but it does clarify when and how old age really begins. And, according to current data, be “older” It is something that, biologically speaking, occurs much later than most imagine.
