(1) יהוה spoke to Moses and Aaron, saying: (2) Take a [separate] census of the Kohathites among the Levites, by the clans of their ancestral house, (3) from the age of thirty years up to the age of fifty, all who are subject to service, to perform tasks for the Tent of Meeting. (4) This is the responsibility of the Kohathites in the Tent of Meeting: the most sacred objects.
(24) These are the sons of Levi by clans, with their clan chiefs as they were enrolled, with a list of their names by heads, who did the work of the service of the House of the Eternal from the age of twenty and upward. (25) For David said, “The Eternal God of Israel has given rest to God's people and made the divine dwelling in Jerusalem forever. (26) Therefore the Levites need not carry the Tabernacle and all its various service vessels.” (27) Among the last acts of David was the counting of the Levites from the age of twenty and upward. (28) For their appointment was alongside the Aaronites for the service of the House of the Eternal, to look after the courts and the chambers, and the purity of all the holy things, and the performance of the service of the House of God.
(8) In the second year after their arrival at the House of God, at Jerusalem, in the second month, Zerubbabel son of Shealtiel and Jeshua son of Jozadak, and the rest of their brother priests and Levites, and all who had come from the captivity to Jerusalem, as their first step appointed Levites from the age of twenty and upward to supervise the work of the House of the Eternal. (9) Jeshua, his sons and brothers, Kadmiel and his sons, the sons of Judah, together were appointed in charge of those who did the work in the House of God; also the sons of Henadad, their sons and brother Levites.
From twenty-five years — But in another passage, it states, (Numbers 4:3) “from thirty years old [and upwards … all that enter into the host to do the work in the tabernacle]”! How are these apparently contradictory passages to be reconciled? In the following way: From twenty five years on he (the Levite) comes to learn the laws regulating the service, and he studies for five years, and at the age of thirty he may actually do the service. — From here we may derive the principle that a pupil who does not see an auspicious omen (i. e. success) in his study during five years will never see it. (Sifrei Bamidbar 62; Chullin 24a.)
This is for the Levites - Its meaning is, this is the set time of service which pertains to the Levites. The verse reading from thirty years and upward (Num. 4:23) does not contradict our verse, for from thirty years and upward refers to the service of bearing burdens (Num. 4:24), while our verse, which reads from twenty and five years all and upward, refers to the service in the work of the tent of meeting.
To do the service from the age of twenty. David pushed back the time for education to twenty years old. The reason is explained, "for David said", for David explained that when the Torah said from 30 years old, that was only in the wilderness, for then they had to carry on their shoulders and they needed people of full strength, and "thirty years is for strength" but after "God has given rest to God's people" and then "the Levites don't have to carry the Tabernacle" so there was no need for them to be 30...
(כא) הוּא הָיָה אוֹמֵר, בֶּן חָמֵשׁ שָׁנִים לַמִּקְרָא, בֶּן עֶשֶׂר לַמִּשְׁנָה, בֶּן שְׁלשׁ עֶשְׂרֵה לַמִּצְוֹת, בֶּן חֲמֵשׁ עֶשְׂרֵה לַתַּלְמוּד, בֶּן שְׁמֹנֶה עֶשְׂרֵה לַחֻפָּה, בֶּן עֶשְׂרִים לִרְדֹּף, בֶּן שְׁלשִׁים לַכֹּחַ, בֶּן אַרְבָּעִים לַבִּינָה, בֶּן חֲמִשִּׁים לָעֵצָה, בֶּן שִׁשִּׁים לַזִּקְנָה, בֶּן שִׁבְעִים לַשֵּׂיבָה, בֶּן שְׁמֹנִים לַגְּבוּרָה, בֶּן תִּשְׁעִים לָשׁוּחַ, בֶּן מֵאָה כְּאִלּוּ מֵת וְעָבַר וּבָטֵל מִן הָעוֹלָם:
(21) He used to say: At five years of age the study of Scripture; At ten the study of Mishnah; At thirteen subject to the commandments; At fifteen the study of Talmud; At eighteen the bridal canopy; At twenty for pursuit [of livelihood]; At thirty the peak of strength; At forty wisdom; At fifty able to give counsel; At sixty old age; At seventy fullness of years; At eighty the age of “strength”; At ninety a bent body; At one hundred, as good as dead and gone completely out of the world.
PEAK STRENGTH: At what age are we our strongest? By The Barbell Team -May 22, 2020
We at The Barbell conducted our own survey of the forty-two annual World’s Strongest Man contests (1977-2019, none in 1987) looking at the top three finishers each year. We determined that the average age of World’s Strongest Man medalists was 30 (29.64). The youngest W.S.M. champion was 25, the oldest 37. A greater likelihood of injuries in strongman than powerlifting, as one study shows, may explain the 5-year difference in strength peaks. Also, strongman events tend to involve more athleticism and endurance than the three powerlifts, and this may favor younger men.
People don't become 'adults' until their 30s, say scientists, BBC NEWS 19/3/19
People don't become fully "adult" until they're in their 30s, according to brain scientists.
Currently the UK law says you become a mature adult when you reach the age of 18.
Scientists who study the brain and nervous system say the age at which you become an adult is different for everyone.
Research suggests people aged 18 are still going through changes in the brain which can affect behaviour and make them more likely to develop mental health disorders.
Professor Peter Jones, from Cambridge University, said: "What we're really saying is that to have a definition of when you move from childhood to adulthood looks increasingly absurd.
"It's a much more nuanced transition that takes place over three decades."
He added: "I guess systems like the education system, the health system and the legal system make it convenient for themselves by having definitions."
When you reach 18, you can vote, buy alcohol, get a mortgage and are also treated as an adult if you get in trouble with the police.
Despite this, Professor Jones says he believes experienced criminal judges recognise the difference between a 19-year-old defendant and a "hardened criminal" in their late 30s.
"I think the system is adapting to what's hiding in plain sight, that people don't like (the idea of) a caterpillar turning into a butterfly," he said.
"There isn't a childhood and then an adulthood. People are on a pathway, they're on a trajectory."
Prof Jones is one of a number of experts who are taking part in a neuroscience meeting hosted by the Academy of Medical Sciences in Oxford.
In the early part of the 21st century, Jeffrey Arnett (2000, 2014), like Hall a century before him, introduced a new life stage that he called Emerging Adulthood (EA). In order to offer a comprehensive critique of the concept, it is important to understand Arnett’s conceptualization of EA. Others had been writing about the lives of young adults since the 1980s (Kuh & Pike, 2005), but Arnett coined a name for the period, thereby reifying it in the public imagination (du Bois-Reymond, 2016). He used the term EA sometimes as a descriptor for people 18 to 25 years of age and sometimes as a developmental stage, thus obfuscating the clear differentiation between the two conceptions (Côté, 2014b).
For Arnett, the trait that distinguished this group from adolescence and adulthood was the intense efforts undertaken to “explore a variety of possible life directions in love, work, and worldviews” (2000, p. 469). He borrows from the theories of Erikson, Levinson, and especially Keniston (1971) when he emphasizes the notion of instability, conflict with society, and the search for one’s identity as crucial to this stage. Arnett admits in passing that it is culturally specific, diverse, and not available to everyone, but throughout his writings, EA and its accompanying identity searches are described as the new measure of a healthy young person and a representation of the advancement of an industrially developed society.
Arnett (2000) makes a crucial distinction between adolescence and EA by using a tautological argument—that the two stages are not the same because psychologists treat them differently. He also distinguishes between EA and adulthood by claiming emerging adults (EAs) do not see themselves as adults. Thus the ultimate criteria for determining this stage seems to be consensus by psychologists, who of course are burdened by their own class and ethnic biases, and young people’s self-report. Arnett admits that socio-economic factors (and financial independence) have a significant role in shaping the life experiences of people in their 20s. However, he does not explore the implications of class and ethnic diversity in terms of opportunities available for people in their 20s. His framing of the stage is ahistorical, not rooted in the social and economic realities of people, heteronormative (the stage ends with marriage), and is biased towards the experiences of families with economic and social privilege, in the USA and around the world...
The impact of reifying the period between ages 18 to 25 as a separate stage reflecting fundamental changes that originate within the individual has an impact on addressing current needs that youth have in an era of downsizing and structural adjustment. Youth today face uncertain economic circumstances, stark inequality, and a loss of access to benefits like healthcare, pensions, higher education, and a safety net when there is a loss of jobs. They have responded by organizing around social justice issues.
Mainstream psychological theories (Arnett, 2000) do not refer to this sea change in young adult lives as resulting from a profound loss of compact between government and its young citizens. The main architects of the concept of EA write about the search for identity (which is often referred to as a hallmark of this stage) as a voluntary affair resulting from more opportunities rather than the reality that this search masks—a loss of adequate pathways for fulfillment. While the dominant discourse notes that there is incredible diversity in the lifestyles of this age group, it does not make the important connection between the essentialized traits of EA, socioeconomic status, and ethnicity (Vespa, 2017).
Conceiving of this stage of as one of opportunity rather than deprivation has important consequences. Policy prescriptions for the loss of available jobs in society range from increased and diversified vocational training, higher education, and a host of other methods meant to keep young people out of the job market and in a holding pattern (Giroux, 2012). Governmental policies favor young people remaining in post-secondary educational institutions by tying aid to youth with full-time membership in educational institutions. A recent New York state law granting free tuition in state-run higher education institutions stipulated that students needed to be in school full-time in order to qualify. This favors the middle class and at the same time keeps a vulnerable group out of the labor market (Feldman, 2017). The majority of job opportunities available to young people have been short term, contractual, and low wage in nature, with few benefits attached to employment. Youth-related policies enacted in this new era seem ill-suited to the post-industrial society (Dwyer, Smith, Tyler, & Wyn, 2005).